485BPOS

As filed with the Securities and Exchange Commission on January 18, 2018

Securities Act File No. 333-173276

Investment Company Act of 1940 File No. 811-22542

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933	☒
Pre-Effective Amendment No.
Post-Effective Amendment No. 140

and/or

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940 ☒

Amendment No. 146

SSGA Active Trust

(Exact Name of Registrant as Specified in Charter)

One Lincoln Street

Boston, Massachusetts 02111

(Address of Principal Executive Offices)

Registrant’s Telephone Number: (617) 664-7037

Joshua A. Weinberg, Esq.

Managing Director and Managing Counsel

SSGA Funds Management, Inc.

One Lincoln Street

Boston, Massachusetts 02111

(Name and Address of Agent for Service)

Copies to:

W. John McGuire

Morgan, Lewis & Bockius LLP

1111 Pennsylvania Avenue, NW

Washington, DC 20004

It is proposed that this filing will become effective:

☒ immediately upon filing pursuant to Rule 485, paragraph (b)

☐ on                     pursuant to Rule 485, paragraph (b)

☐ 60 days after filing pursuant to Rule 485, paragraph (a)(1)

☐ on                     pursuant to Rule 485, paragraph (a)(1)

☐ 75 days after filing pursuant to Rule 485, paragraph (a)(2)

☐ on                      pursuant to Rule 485, paragraph (a)(2)

☐ As soon as practicable after the effective date of this registration statement.

SSGA MASTER TRUST HAS ALSO EXECUTED THIS REGISTRATION STATEMENT

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, and the Investment Company Act of 1940, as amended, SSGA Active Trust, the Registrant, certifies that it meets all of the requirements for effectiveness of this Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933, as amended, and has duly caused this Amendment to the Registration Statement to be signed on its behalf by the undersigned, thereunder duly authorized, in the City of Boston and the Commonwealth of Massachusetts on the 18^th day of January, 2018.

	SSGA Active Trust
By:	/s/ Ellen M. Needham
	Ellen M. Needham
	President

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to the Registration Statement has been signed below by the following persons in the capacities and on the date indicated:

SIGNATURES	TITLE	DATE
/s/ Bonny E. Boatman*	Trustee	January 18, 2018
Bonny E. Boatman
/s/ Dwight D. Churchill*	Trustee	January 18, 2018
Dwight D. Churchill
/s/ David M. Kelly*	Trustee	January 18, 2018
David M. Kelly
/s/ Frank Nesvet*	Trustee	January 18, 2018
Frank Nesvet
/s/ Carl G. Verboncoeur*	Trustee	January 18, 2018
Carl G. Verboncoeur
/s/ James E. Ross*	Trustee	January 18, 2018
James E. Ross
/s/ Ellen M. Needham Ellen M. Needham	President and Principal Executive Officer	January 18, 2018
/s/ Bruce S. Rosenberg Bruce S. Rosenberg	Treasurer and Principal Financial Officer	January 18, 2018

*By:	/s/ Jesse D. Hallee
	Jesse D. Hallee
	As Attorney-in-Fact Pursuant to Power of Attorney

SIGNATURES

SSGA Master Trust has duly caused this Post-Effective Amendment No. 140 to the Registration Statement on Form N-1A of the SSGA Active Trust (the “Registrant”) to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Boston and the Commonwealth of Massachusetts on January 18, 2018.

SSGA MASTER TRUST
By:	/s/ Ellen M. Needham
	Ellen M. Needham
	President

This Registration Statement on Form N-1A of the Registrant has been signed below by the following persons, solely in the capacities indicated, on January 18, 2018.

SIGNATURE	TITLE
/s/ Bonny E. Boatman*	Trustee
Bonny E. Boatman
/s/ Dwight D. Churchill*	Trustee
Dwight D. Churchill
/s/ David M. Kelly*	Trustee
David M. Kelly
/s/ Frank Nesvet*	Trustee
Frank Nesvet
/s/ Carl G. Verboncoeur*	Trustee
Carl G. Verboncoeur
/s/ James E. Ross* James E. Ross	Trustee
/s/ Ellen M. Needham Ellen M. Needham	President and Principal Executive Officer
/s/ Bruce S. Rosenberg	Treasurer and Principal Financial Officer
Bruce S. Rosenberg

*By:	/s/ Jesse D. Hallee
	Jesse D. Hallee
	As Attorney-in-Fact Pursuant to Power of Attorney

Exhibit Index

Exhibit No.
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CAL	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Mar. 17, 2016
Registrant Name	dei_EntityRegistrantName	SSGA Active Trust
Central Index Key	dei_EntityCentralIndexKey	0001516212
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Mar. 17, 2016
Document Effective Date	dei_DocumentEffectiveDate	Dec. 17, 2017
Prospectus Date	rr_ProspectusDate	Dec. 17, 2017

XML

SPDR(R) SSGA U.S. Sector Rotation ETF

FUND SUMMARY

SPDR^® SSGA U.S. Sector Rotation ETF

INVESTMENT OBJECTIVE

The SPDR SSGA U.S. Sector Rotation ETF (the “Fund”) seeks to provide capital appreciation.

FEES AND EXPENSES OF THE FUND

The table below describes the fees and expenses that you may pay if you buy and hold shares of the Fund (“Fund Shares”). This table and the Example below reflect the expenses of both the Fund and the Portfolio (defined below) and do not reflect brokerage commissions you may pay on purchases and sales of Fund Shares.

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment):

Annual Fund Operating Expenses	SPDR(R) SSGA U.S. Sector Rotation ETF SPDR(R) SSGA U.S. Sector Rotation ETF	[1]
Management fees
Distribution and service (12b-1) fees
Other expenses		[2]
Total annual Fund operating expenses

EXAMPLE:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated, and then sell all of your Fund Shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	Year 1	Year 3
SPDR(R) SSGA U.S. Sector Rotation ETF | SPDR(R) SSGA U.S. Sector Rotation ETF | USD ($)

PORTFOLIO TURNOVER:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund Shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. The Fund’s portfolio turnover rate has been omitted because the Fund had not commenced investment operations as of the date of this Prospectus.

THE FUND’S PRINCIPAL INVESTMENT STRATEGY

Under normal circumstances, the Fund invests substantially all of its assets in the State Street U.S. Sector Rotation Portfolio (the “Portfolio”), a separate series of the SSGA Master Trust with an identical investment objective as the Fund. As a result, the Fund invests indirectly through the Portfolio.

The Portfolio is a “fund of funds,” meaning that it invests its assets in other exchange-traded funds (“ETFs”) rather than in securities of individual companies. In seeking to provide exposure to certain sectors represented within the S&P 500 Index, the Adviser employs a tactical sector allocation strategy and allocates the Portfolio’s assets to any combination of the Select Sector SPDR^® exchange traded funds (the “Underlying ETFs”), each of which is an ETF advised by the Adviser or its affiliates that provides U.S. equity market sector exposure through its investments in sector-specific equity securities. As of [     ], the investment universe of the Underlying ETFs comprised companies in the consumer discretionary, consumer staples, energy, financial, health care, industrials, materials, technology and utilities sectors, although this may change from time to time.

The Portfolio’s allocation among equity sectors comprising the Underlying ETFs will be in proportions consistent with the Adviser’s evaluation of the expected returns and risks of each equity sector, as well as the allocation that, in the Adviser’s view, will best meet the Fund’s investment objective. The allocations to each sector will change over time as the Adviser’s expectations of each sector shift. The Portfolio’s indirect holdings by virtue of investing in the Underlying ETFs consist primarily of securities issued by large-capitalization companies.

The Adviser’s investment decisions are driven by a proprietary process supported by a quantitative sector selection model. The model incorporates macroeconomic, financial and market data to arrive at a one-month return forecast for each equity sector. The Adviser uses the results of the model and applies its qualitative judgment to construct a portfolio consisting of the Underlying ETFs, seeking the optimal mix of equity sector positions to maximize expected return while satisfying the Adviser’s predicted risk target and complying with the Portfolio’s investment constraints. The Adviser may make a qualitative judgment not to fully implement the results of the model if it believes that the model did not take into account all of the information relevant to the Portfolio’s investments, or that a different evaluation or weighting of the information relating to the Portfolio’s investments might be more appropriate. The Adviser typically rebalances the portfolio on a monthly basis, but rebalancing could occur more frequently depending on market conditions. The Adviser may engage in frequent trading to achieve the Fund’s investment objective, which may result in turnover in excess of 100%.

PRINCIPAL RISKS OF INVESTING IN THE FUND

As with all investments, there are certain risks of investing in the Fund. Fund Shares will change in value, and you could lose money by investing in the Fund. An investment in the Fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Because the Fund invests substantially all of its assets in the Portfolio, it is subject to substantially the same risks as those associated with the direct ownership of the securities in which the Portfolio invests.

Exchange Traded Products Risk: The Fund is subject to substantially the same risks as those associated with the direct ownership of the securities represented by the exchange-traded products (“ETPs”) in which the Portfolio invests. In addition, the shares of certain ETPs may trade at a premium or discount to their intrinsic value (i.e., the market value may differ from the net asset value of an ETF’s shares) for a number of reasons. For example, supply and demand for shares of an Underlying ETF or market disruptions may cause the market price of the Underlying ETF to deviate from the value of the Underlying ETF’s investments, which may be exacerbated in less liquid markets. By investing in ETPs, the Fund indirectly bears the Portfolio’s proportionate share of any fees and expenses (e.g. management, custody, accounting, and administration) of the ETP, if applicable, in addition to the fees and expenses that the Fund and its shareholders directly bear in connection with the Portfolio’s and the Fund’s operations. The Portfolio, and indirectly the Fund, is subject to the following risks indirectly through its investments in ETPs.

Affiliated ETP Risk: The Adviser may receive management or other fees from the ETPs (“Affiliated ETPs”) in which the Portfolio may invest, as well as a management fee for managing the Fund. It is possible that a conflict of interest among the Portfolio and the Affiliated ETPs could affect how the Adviser fulfills its fiduciary duties to the Portfolio and the Affiliated ETPs. Because the amount of the investment management fees to be retained by the Adviser may differ depending upon the Affiliated ETPs in which the Portfolio invests, there is a conflict of interest for the Adviser in selecting the Affiliated ETPs. In addition, the Adviser may have an incentive to take into account the effect on an Affiliated ETP in which the Portfolio may invest in determining whether, and under what circumstances, to purchase or sell shares in that Affiliated ETP. Although the Adviser takes steps to address the conflicts of interest, it is possible that the conflicts could impact the Portfolio and, therefore, the Fund.

Asset Allocation Risk: The Fund’s investment performance depends upon the successful allocation by the Adviser of the Portfolio’s assets among asset classes, geographical regions, industry sectors, and specific issuers and investments. There is no guarantee that the Adviser’s allocation techniques and decisions will produce the desired results.

Consumer Discretionary Sector Risk: The success of consumer product manufacturers and retailers is tied closely to the performance of the overall domestic and global economy, interest rates, competition and consumer confidence. Success depends heavily on disposable household income and consumer spending. Also, companies in the consumer discretionary sector may be subject to severe competition, which may have an adverse impact on their respective profitability. Changes in demographics and consumer tastes can also affect the demand for, and success of, consumer products and services in the marketplace.

Consumer Staples Sector Risk: Consumer staples companies are subject to government regulation affecting their products which may negatively impact such companies’ performance. For instance, government regulations may affect the permissibility of using various food additives and production methods of companies that make food products, which could affect company profitability. Tobacco companies may be adversely affected by the adoption of proposed legislation and/or by litigation. Also, the success of food, beverage, household and personal product companies may be strongly affected by consumer interest, marketing campaigns and other factors affecting supply and demand, including performance of the overall domestic and global economy, interest rates, competition and consumer confidence and spending.

Energy Sector Risk: Issuers in energy-related industries can be significantly affected by fluctuations in energy prices and supply and demand of energy fuels. Markets for various energy-related commodities can have significant volatility, and are subject to control or manipulation by large producers or purchasers. Companies in the energy sector may need to make substantial expenditures, and to incur significant amounts of debt, in order to maintain or expand their reserves. Oil and gas exploration and production can be significantly affected by natural disasters as well as changes in exchange rates, interest rates, government regulation, world events and economic conditions. These companies may be at risk for environmental damage claims.

Equity Investing Risk: The market prices of equity securities owned by the Portfolio may go up or down, sometimes rapidly or unpredictably. The value of a security may decline for a number of reasons that may directly relate to the issuer and also may decline due to general industry or market conditions that are not specifically related to a particular company. In addition, equity markets tend to move in cycles, which may cause stock prices to fall over short or extended periods of time.

Financial Sector Risk: Financial services companies are subject to extensive governmental regulation which may limit both the amounts and types of loans and other financial commitments they can make, the interest rates and fees they can charge, the scope of their activities, the prices they can charge and the amount of capital they must maintain. Profitability is largely dependent on the availability and cost of capital funds and can fluctuate significantly when interest rates change or due to increased competition. In addition, deterioration of the credit markets generally may cause an adverse impact in a broad range of markets, including U.S. and international credit and interbank money markets generally, thereby affecting a wide range of financial institutions and markets. Certain events in the financial sector may cause an unusually high degree of volatility in the financial markets, both domestic and foreign, and cause certain financial services companies to incur large losses. Securities of financial services companies may experience a dramatic decline in value when such companies experience substantial declines in the valuations of their assets, take action to raise capital (such as the issuance of debt or equity securities), or cease operations. Credit losses resulting from financial difficulties of borrowers and financial losses associated with investment activities can negatively impact the sector. Insurance companies may be subject to severe price competition. Adverse economic, business or political developments affecting real estate could have a major effect on the value of real estate securities (which include real estate investment trusts (“REITs”)). Declining real estate values could adversely affect financial institutions engaged in mortgage finance or other lending or investing activities directly or indirectly connected to the value of real estate.

Health Care Sector Risk: Companies in the health care sector are subject to extensive government regulation and their profitability can be significantly affected by restrictions on government reimbursement for medical expenses, rising costs of medical products and services, pricing pressure (including price discounting), limited product lines and an increased emphasis on the delivery of healthcare through outpatient services. Companies in the health care sector are heavily dependent on obtaining and defending patents, which may be time consuming and costly, and the expiration of patents may also adversely affect the profitability of these companies. Health care companies are also subject to extensive litigation based on product liability and similar claims. In addition, their products can become obsolete due to industry innovation, changes in technologies or other market developments. Many new products in the health care sector require significant research and development and may be subject to regulatory approvals, all of which may be time consuming and costly with no guarantee that any product will come to market.

Industrial Sector Risk: Industrial companies are affected by supply and demand both for their specific product or service and for industrial sector products in general. Government regulation, world events, exchange rates and economic conditions, technological developments and liabilities for environmental damage and general civil liabilities will likewise affect the performance of these companies. Aerospace and defense companies, a component of the industrial sector, can be significantly affected by government spending policies because companies involved in this industry rely, to a significant extent, on U.S. and foreign government demand for their products and services. Thus, the financial condition of, and investor interest in, aerospace and defense companies are heavily influenced by governmental defense spending policies which are typically under pressure from efforts to control the U.S. (and other) government budgets. Transportation securities, a component of the industrial sector, are cyclical and have occasional sharp price movements which may result from changes in the economy, fuel prices, labor agreements and insurance costs.

Large-Capitalization Securities Risk: Returns on investments in securities of large companies could trail the returns on investments in securities of smaller and mid-sized companies. Larger companies may be unable to respond as quickly as smaller and mid-sized companies to competitive challenges or to changes in business, product, financial, or other market conditions. Larger companies may not be able to maintain growth at the high rates that may be achieved by well-managed smaller and mid-sized companies.

Management Risk: The Portfolio is actively managed. The Adviser’s judgments about the attractiveness, relative value, or potential appreciation of a particular sector, security, commodity or investment strategy may prove to be incorrect, and may cause the Portfolio and, therefore, the Fund, to incur losses. There can be no assurance that the Adviser’s investment techniques and decisions will produce the desired results.

Market Risk: The Portfolio’s investments are subject to changes in general economic conditions, and general market fluctuations and the risks inherent in investment in securities markets. Investment markets can be volatile and prices of investments can change substantially due to various factors including, but not limited to, economic growth or recession, changes in interest rates, changes in the actual or perceived creditworthiness of issuers, and general market liquidity. The Portfolio is subject to the risk that geopolitical events will disrupt securities markets and adversely affect global economies and markets.

Master/Feeder Structure Risk: The Fund pursues its objective by investing substantially all of its assets in another pooled investment vehicle (a “master fund”). The ability of the Fund to meet its investment objective is directly related to the ability of the master fund to meet its investment objective. The Adviser or an affiliate serves as investment adviser to the master fund, leading to potential conflicts of interest. The Fund will bear its pro rata portion of the expenses incurred by the master fund. Substantial redemptions by other investors in a master fund may affect the master fund’s investment program adversely and limit the ability of the master fund to achieve its objective.

Materials Sector Risk: Many materials companies are significantly affected by the level and volatility of commodity prices, exchange rates, import controls, worldwide competition, environmental policies and consumer demand. At times, worldwide production of industrial materials has exceeded demand as a result of over-building or economic downturns, leading to poor investment returns or losses. Other risks may include liabilities for environmental damage and general civil liabilities, depletion of resources, and mandated expenditures for safety and pollution control. The materials sector may also be affected by economic cycles, technical progress, labor relations, and government regulations.

Modeling Risk: The Adviser uses quantitative models in an effort to enhance returns and manage risk. Any imperfections, errors or limitations in these models could limit any benefit to the Portfolio from the use of the models, or could result in incorrect outputs or in investment outcomes different from or opposite to those expected or desired by the Adviser. There can be no assurance that the models will behave as expected in all market conditions. In addition, computer programming used to create quantitative models, or the data on which such models operate, might contain one or more errors.

Non-Diversification Risk: As a “non-diversified” mutual fund, the Portfolio may hold a smaller number of portfolio securities than many other funds. To the extent the Portfolio invests in a relatively small number of issuers, a decline in the market value of a particular security held by the Portfolio may affect its value more than if it invested in a larger number of issuers. The value of the Portfolio’s shares may be more volatile than the values of shares of more diversified funds.

Portfolio Turnover Risk: Frequent purchases and sales of portfolio securities may result in higher Portfolio expenses and may result in more significant distributions of short-term capital gains to investors, which are taxed as ordinary income.

Real Estate Securities Risk: An investment in a real property company may be subject to risks similar to those associated with direct ownership of real estate, including, by way of example, the possibility of declines in the value of real estate, losses from casualty or condemnation, and changes in local and general economic conditions, supply and demand, interest rates, environmental liability, zoning laws, regulatory limitations on rents, property taxes, and operating expenses. Some real property companies have limited diversification because they invest in a limited number of properties, a narrow geographic area, or a single type of property.

REIT Risk: REITs are subject to the risks associated with investing in the securities of real property companies. In particular, REITs may be affected by changes in the values of the underlying properties that they own or operate. Further, REITs are dependent upon specialized management skills, and their investments may be concentrated in relatively few properties, or in a small geographic area or a single property type. REITs are also subject to heavy cash flow dependency and, as a result, are particularly reliant on the proper functioning of capital markets. A variety of economic and other factors may adversely affect a lessee’s ability to meet its obligations to a REIT. In the event of a default by a lessee, the REIT may experience delays in enforcing its rights as a lessor and may incur substantial costs associated in protecting its investments. In addition, a REIT could fail to qualify for favorable regulatory treatment.

Technology Sector Risk: Market or economic factors impacting technology companies and companies that rely heavily on technological advances could have a major effect on the value of the Portfolio’s investments. The value of stocks of technology companies and companies that rely heavily on technology is particularly vulnerable to rapid changes in technology product cycles, rapid product obsolescence, government regulation and competition, both domestically and internationally, including competition from foreign competitors with lower production costs. Stocks of technology companies and companies that rely heavily on technology, especially those of smaller, less-seasoned companies, tend to be more volatile than the overall market. Technology companies are heavily dependent on patent and intellectual property rights, the loss or impairment of which may adversely affect profitability. Additionally, companies in the technology sector may face dramatic and often unpredictable changes in growth rates and competition for the services of qualified personnel.

Unconstrained Sector Risk: The Portfolio may invest a substantial portion of its assets within one or more economic sectors or industries, which may change from time to time. Greater investment focus on one or more sectors or industries increases the potential for volatility and the risk that events negatively affecting such sectors or industries could reduce returns, potentially causing the value of the Portfolio’s shares to decrease, perhaps significantly.

Utilities Sector Risk: Stock prices for companies in the utilities sector are affected by supply and demand, operating costs, government regulation, environmental actors, liabilities for environmental damage and general civil liabilities, rate caps or rate changes. Utility companies are affected by supply and demand, operating costs, government regulation, environmental factors, liabilities for environmental damage and general civil liabilities, and rate caps or rate changes. Although rate changes of a regulated utility usually fluctuate in approximate correlation with financing costs, due to political and regulatory factors rate changes ordinarily occur only following a delay after the changes in financing costs. This factor will tend to favorably affect a regulated utility company’s earnings and dividends in times of decreasing costs, but conversely, will tend to adversely affect earnings and dividends when costs are rising. The value of regulated utility equity securities may tend to have an inverse relationship to the movement of interest rates. Certain utility companies have experienced full or partial deregulation in recent years. These utility companies are frequently more similar to industrial companies in that they are subject to greater competition and have been permitted by regulators to diversify outside of their original geographic regions and their traditional lines of business. These opportunities may permit certain utility companies to earn more than their traditional regulated rates of return. Some companies, however, may be forced to defend their core business and may be less profitable. In addition, natural disasters, terrorist attacks, government intervention or other factors may render a utility company’s equipment unusable or obsolete and negatively impact profitability.

Among the risks that may affect utility companies are the following: risks of increases in fuel and other operating costs; the high cost of borrowing to finance capital construction during inflationary periods; restrictions on operations and increased costs and delays associated with compliance with environmental and nuclear safety regulations; and the difficulties involved in obtaining natural gas for resale or fuel for generating electricity at reasonable prices. Other risks include those related to the construction and operation of nuclear power plants, the effects of energy conservation and the effects of regulatory changes.

FUND PERFORMANCE

The Fund had not yet commenced operations as of the date of this Prospectus and therefore does not have any performance history. Once the Fund has completed a full calendar year of operations, a bar chart and table will be included that will provide some indication of the risks of investing in the Fund by showing the variability of the Fund’s returns based on net assets and comparing the Fund’s performance to a broad-based securities index. When available, the Fund will make updated performance information available by calling 1-866-787-2257 or visiting the Fund’s website: https://www.spdrs.com.

[1] [The Fund has adopted a Distribution and Service (12b-1) Plan pursuant to which payments of up to 0.25% of average daily net assets may be made; however, the Fund’s Board of Trustees has determined that no such payments will be made through the next twelve (12) months of operation.]

[2] Other expenses are based on estimated amounts for the current fiscal year.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	SSGA Active Trust
Prospectus Date	rr_ProspectusDate	Dec. 17, 2017
SPDR(R) SSGA U.S. Sector Rotation ETF
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY SPDR® SSGA U.S. Sector Rotation ETF
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The SPDR SSGA U.S. Sector Rotation ETF (the “Fund”) seeks to provide capital appreciation.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may pay if you buy and hold shares of the Fund (“Fund Shares”). This table and the Example below reflect the expenses of both the Fund and the Portfolio (defined below) and do not reflect brokerage commissions you may pay on purchases and sales of Fund Shares.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment):
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	PORTFOLIO TURNOVER:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund Shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. The Fund’s portfolio turnover rate has been omitted because the Fund had not commenced investment operations as of the date of this Prospectus.
Expense Exchange Traded Fund Commissions [Text]	rr_ExpenseExchangeTradedFundCommissions	This table and the Example below reflect the expenses of both the Fund and the Portfolio (defined below) and do not reflect brokerage commissions you may pay on purchases and sales of Fund Shares.
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Other expenses are based on estimated amounts for the current fiscal year.
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated, and then sell all of your Fund Shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	THE FUND’S PRINCIPAL INVESTMENT STRATEGY
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal circumstances, the Fund invests substantially all of its assets in the State Street U.S. Sector Rotation Portfolio (the “Portfolio”), a separate series of the SSGA Master Trust with an identical investment objective as the Fund. As a result, the Fund invests indirectly through the Portfolio. The Portfolio is a “fund of funds,” meaning that it invests its assets in other exchange-traded funds (“ETFs”) rather than in securities of individual companies. In seeking to provide exposure to certain sectors represented within the S&P 500 Index, the Adviser employs a tactical sector allocation strategy and allocates the Portfolio’s assets to any combination of the Select Sector SPDR® exchange traded funds (the “Underlying ETFs”), each of which is an ETF advised by the Adviser or its affiliates that provides U.S. equity market sector exposure through its investments in sector-specific equity securities. As of [     ], the investment universe of the Underlying ETFs comprised companies in the consumer discretionary, consumer staples, energy, financial, health care, industrials, materials, technology and utilities sectors, although this may change from time to time. The Portfolio’s allocation among equity sectors comprising the Underlying ETFs will be in proportions consistent with the Adviser’s evaluation of the expected returns and risks of each equity sector, as well as the allocation that, in the Adviser’s view, will best meet the Fund’s investment objective. The allocations to each sector will change over time as the Adviser’s expectations of each sector shift. The Portfolio’s indirect holdings by virtue of investing in the Underlying ETFs consist primarily of securities issued by large-capitalization companies. The Adviser’s investment decisions are driven by a proprietary process supported by a quantitative sector selection model. The model incorporates macroeconomic, financial and market data to arrive at a one-month return forecast for each equity sector. The Adviser uses the results of the model and applies its qualitative judgment to construct a portfolio consisting of the Underlying ETFs, seeking the optimal mix of equity sector positions to maximize expected return while satisfying the Adviser’s predicted risk target and complying with the Portfolio’s investment constraints. The Adviser may make a qualitative judgment not to fully implement the results of the model if it believes that the model did not take into account all of the information relevant to the Portfolio’s investments, or that a different evaluation or weighting of the information relating to the Portfolio’s investments might be more appropriate. The Adviser typically rebalances the portfolio on a monthly basis, but rebalancing could occur more frequently depending on market conditions. The Adviser may engage in frequent trading to achieve the Fund’s investment objective, which may result in turnover in excess of 100%.
Risk [Heading]	rr_RiskHeading	PRINCIPAL RISKS OF INVESTING IN THE FUND
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	As with all investments, there are certain risks of investing in the Fund. Fund Shares will change in value, and you could lose money by investing in the Fund. An investment in the Fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Because the Fund invests substantially all of its assets in the Portfolio, it is subject to substantially the same risks as those associated with the direct ownership of the securities in which the Portfolio invests. Exchange Traded Products Risk: The Fund is subject to substantially the same risks as those associated with the direct ownership of the securities represented by the exchange-traded products (“ETPs”) in which the Portfolio invests. In addition, the shares of certain ETPs may trade at a premium or discount to their intrinsic value (i.e., the market value may differ from the net asset value of an ETF’s shares) for a number of reasons. For example, supply and demand for shares of an Underlying ETF or market disruptions may cause the market price of the Underlying ETF to deviate from the value of the Underlying ETF’s investments, which may be exacerbated in less liquid markets. By investing in ETPs, the Fund indirectly bears the Portfolio’s proportionate share of any fees and expenses (e.g. management, custody, accounting, and administration) of the ETP, if applicable, in addition to the fees and expenses that the Fund and its shareholders directly bear in connection with the Portfolio’s and the Fund’s operations. The Portfolio, and indirectly the Fund, is subject to the following risks indirectly through its investments in ETPs. Affiliated ETP Risk: The Adviser may receive management or other fees from the ETPs (“Affiliated ETPs”) in which the Portfolio may invest, as well as a management fee for managing the Fund. It is possible that a conflict of interest among the Portfolio and the Affiliated ETPs could affect how the Adviser fulfills its fiduciary duties to the Portfolio and the Affiliated ETPs. Because the amount of the investment management fees to be retained by the Adviser may differ depending upon the Affiliated ETPs in which the Portfolio invests, there is a conflict of interest for the Adviser in selecting the Affiliated ETPs. In addition, the Adviser may have an incentive to take into account the effect on an Affiliated ETP in which the Portfolio may invest in determining whether, and under what circumstances, to purchase or sell shares in that Affiliated ETP. Although the Adviser takes steps to address the conflicts of interest, it is possible that the conflicts could impact the Portfolio and, therefore, the Fund. Asset Allocation Risk: The Fund’s investment performance depends upon the successful allocation by the Adviser of the Portfolio’s assets among asset classes, geographical regions, industry sectors, and specific issuers and investments. There is no guarantee that the Adviser’s allocation techniques and decisions will produce the desired results. Consumer Discretionary Sector Risk: The success of consumer product manufacturers and retailers is tied closely to the performance of the overall domestic and global economy, interest rates, competition and consumer confidence. Success depends heavily on disposable household income and consumer spending. Also, companies in the consumer discretionary sector may be subject to severe competition, which may have an adverse impact on their respective profitability. Changes in demographics and consumer tastes can also affect the demand for, and success of, consumer products and services in the marketplace. Consumer Staples Sector Risk: Consumer staples companies are subject to government regulation affecting their products which may negatively impact such companies’ performance. For instance, government regulations may affect the permissibility of using various food additives and production methods of companies that make food products, which could affect company profitability. Tobacco companies may be adversely affected by the adoption of proposed legislation and/or by litigation. Also, the success of food, beverage, household and personal product companies may be strongly affected by consumer interest, marketing campaigns and other factors affecting supply and demand, including performance of the overall domestic and global economy, interest rates, competition and consumer confidence and spending. Energy Sector Risk: Issuers in energy-related industries can be significantly affected by fluctuations in energy prices and supply and demand of energy fuels. Markets for various energy-related commodities can have significant volatility, and are subject to control or manipulation by large producers or purchasers. Companies in the energy sector may need to make substantial expenditures, and to incur significant amounts of debt, in order to maintain or expand their reserves. Oil and gas exploration and production can be significantly affected by natural disasters as well as changes in exchange rates, interest rates, government regulation, world events and economic conditions. These companies may be at risk for environmental damage claims. Equity Investing Risk: The market prices of equity securities owned by the Portfolio may go up or down, sometimes rapidly or unpredictably. The value of a security may decline for a number of reasons that may directly relate to the issuer and also may decline due to general industry or market conditions that are not specifically related to a particular company. In addition, equity markets tend to move in cycles, which may cause stock prices to fall over short or extended periods of time. Financial Sector Risk: Financial services companies are subject to extensive governmental regulation which may limit both the amounts and types of loans and other financial commitments they can make, the interest rates and fees they can charge, the scope of their activities, the prices they can charge and the amount of capital they must maintain. Profitability is largely dependent on the availability and cost of capital funds and can fluctuate significantly when interest rates change or due to increased competition. In addition, deterioration of the credit markets generally may cause an adverse impact in a broad range of markets, including U.S. and international credit and interbank money markets generally, thereby affecting a wide range of financial institutions and markets. Certain events in the financial sector may cause an unusually high degree of volatility in the financial markets, both domestic and foreign, and cause certain financial services companies to incur large losses. Securities of financial services companies may experience a dramatic decline in value when such companies experience substantial declines in the valuations of their assets, take action to raise capital (such as the issuance of debt or equity securities), or cease operations. Credit losses resulting from financial difficulties of borrowers and financial losses associated with investment activities can negatively impact the sector. Insurance companies may be subject to severe price competition. Adverse economic, business or political developments affecting real estate could have a major effect on the value of real estate securities (which include real estate investment trusts (“REITs”)). Declining real estate values could adversely affect financial institutions engaged in mortgage finance or other lending or investing activities directly or indirectly connected to the value of real estate. Health Care Sector Risk: Companies in the health care sector are subject to extensive government regulation and their profitability can be significantly affected by restrictions on government reimbursement for medical expenses, rising costs of medical products and services, pricing pressure (including price discounting), limited product lines and an increased emphasis on the delivery of healthcare through outpatient services. Companies in the health care sector are heavily dependent on obtaining and defending patents, which may be time consuming and costly, and the expiration of patents may also adversely affect the profitability of these companies. Health care companies are also subject to extensive litigation based on product liability and similar claims. In addition, their products can become obsolete due to industry innovation, changes in technologies or other market developments. Many new products in the health care sector require significant research and development and may be subject to regulatory approvals, all of which may be time consuming and costly with no guarantee that any product will come to market. Industrial Sector Risk: Industrial companies are affected by supply and demand both for their specific product or service and for industrial sector products in general. Government regulation, world events, exchange rates and economic conditions, technological developments and liabilities for environmental damage and general civil liabilities will likewise affect the performance of these companies. Aerospace and defense companies, a component of the industrial sector, can be significantly affected by government spending policies because companies involved in this industry rely, to a significant extent, on U.S. and foreign government demand for their products and services. Thus, the financial condition of, and investor interest in, aerospace and defense companies are heavily influenced by governmental defense spending policies which are typically under pressure from efforts to control the U.S. (and other) government budgets. Transportation securities, a component of the industrial sector, are cyclical and have occasional sharp price movements which may result from changes in the economy, fuel prices, labor agreements and insurance costs. Large-Capitalization Securities Risk: Returns on investments in securities of large companies could trail the returns on investments in securities of smaller and mid-sized companies. Larger companies may be unable to respond as quickly as smaller and mid-sized companies to competitive challenges or to changes in business, product, financial, or other market conditions. Larger companies may not be able to maintain growth at the high rates that may be achieved by well-managed smaller and mid-sized companies. Management Risk: The Portfolio is actively managed. The Adviser’s judgments about the attractiveness, relative value, or potential appreciation of a particular sector, security, commodity or investment strategy may prove to be incorrect, and may cause the Portfolio and, therefore, the Fund, to incur losses. There can be no assurance that the Adviser’s investment techniques and decisions will produce the desired results. Market Risk: The Portfolio’s investments are subject to changes in general economic conditions, and general market fluctuations and the risks inherent in investment in securities markets. Investment markets can be volatile and prices of investments can change substantially due to various factors including, but not limited to, economic growth or recession, changes in interest rates, changes in the actual or perceived creditworthiness of issuers, and general market liquidity. The Portfolio is subject to the risk that geopolitical events will disrupt securities markets and adversely affect global economies and markets. Master/Feeder Structure Risk: The Fund pursues its objective by investing substantially all of its assets in another pooled investment vehicle (a “master fund”). The ability of the Fund to meet its investment objective is directly related to the ability of the master fund to meet its investment objective. The Adviser or an affiliate serves as investment adviser to the master fund, leading to potential conflicts of interest. The Fund will bear its pro rata portion of the expenses incurred by the master fund. Substantial redemptions by other investors in a master fund may affect the master fund’s investment program adversely and limit the ability of the master fund to achieve its objective. Materials Sector Risk: Many materials companies are significantly affected by the level and volatility of commodity prices, exchange rates, import controls, worldwide competition, environmental policies and consumer demand. At times, worldwide production of industrial materials has exceeded demand as a result of over-building or economic downturns, leading to poor investment returns or losses. Other risks may include liabilities for environmental damage and general civil liabilities, depletion of resources, and mandated expenditures for safety and pollution control. The materials sector may also be affected by economic cycles, technical progress, labor relations, and government regulations. Modeling Risk: The Adviser uses quantitative models in an effort to enhance returns and manage risk. Any imperfections, errors or limitations in these models could limit any benefit to the Portfolio from the use of the models, or could result in incorrect outputs or in investment outcomes different from or opposite to those expected or desired by the Adviser. There can be no assurance that the models will behave as expected in all market conditions. In addition, computer programming used to create quantitative models, or the data on which such models operate, might contain one or more errors. Non-Diversification Risk: As a “non-diversified” mutual fund, the Portfolio may hold a smaller number of portfolio securities than many other funds. To the extent the Portfolio invests in a relatively small number of issuers, a decline in the market value of a particular security held by the Portfolio may affect its value more than if it invested in a larger number of issuers. The value of the Portfolio’s shares may be more volatile than the values of shares of more diversified funds. Portfolio Turnover Risk: Frequent purchases and sales of portfolio securities may result in higher Portfolio expenses and may result in more significant distributions of short-term capital gains to investors, which are taxed as ordinary income. Real Estate Securities Risk: An investment in a real property company may be subject to risks similar to those associated with direct ownership of real estate, including, by way of example, the possibility of declines in the value of real estate, losses from casualty or condemnation, and changes in local and general economic conditions, supply and demand, interest rates, environmental liability, zoning laws, regulatory limitations on rents, property taxes, and operating expenses. Some real property companies have limited diversification because they invest in a limited number of properties, a narrow geographic area, or a single type of property. REIT Risk: REITs are subject to the risks associated with investing in the securities of real property companies. In particular, REITs may be affected by changes in the values of the underlying properties that they own or operate. Further, REITs are dependent upon specialized management skills, and their investments may be concentrated in relatively few properties, or in a small geographic area or a single property type. REITs are also subject to heavy cash flow dependency and, as a result, are particularly reliant on the proper functioning of capital markets. A variety of economic and other factors may adversely affect a lessee’s ability to meet its obligations to a REIT. In the event of a default by a lessee, the REIT may experience delays in enforcing its rights as a lessor and may incur substantial costs associated in protecting its investments. In addition, a REIT could fail to qualify for favorable regulatory treatment. Technology Sector Risk: Market or economic factors impacting technology companies and companies that rely heavily on technological advances could have a major effect on the value of the Portfolio’s investments. The value of stocks of technology companies and companies that rely heavily on technology is particularly vulnerable to rapid changes in technology product cycles, rapid product obsolescence, government regulation and competition, both domestically and internationally, including competition from foreign competitors with lower production costs. Stocks of technology companies and companies that rely heavily on technology, especially those of smaller, less-seasoned companies, tend to be more volatile than the overall market. Technology companies are heavily dependent on patent and intellectual property rights, the loss or impairment of which may adversely affect profitability. Additionally, companies in the technology sector may face dramatic and often unpredictable changes in growth rates and competition for the services of qualified personnel. Unconstrained Sector Risk: The Portfolio may invest a substantial portion of its assets within one or more economic sectors or industries, which may change from time to time. Greater investment focus on one or more sectors or industries increases the potential for volatility and the risk that events negatively affecting such sectors or industries could reduce returns, potentially causing the value of the Portfolio’s shares to decrease, perhaps significantly. Utilities Sector Risk: Stock prices for companies in the utilities sector are affected by supply and demand, operating costs, government regulation, environmental actors, liabilities for environmental damage and general civil liabilities, rate caps or rate changes. Utility companies are affected by supply and demand, operating costs, government regulation, environmental factors, liabilities for environmental damage and general civil liabilities, and rate caps or rate changes. Although rate changes of a regulated utility usually fluctuate in approximate correlation with financing costs, due to political and regulatory factors rate changes ordinarily occur only following a delay after the changes in financing costs. This factor will tend to favorably affect a regulated utility company’s earnings and dividends in times of decreasing costs, but conversely, will tend to adversely affect earnings and dividends when costs are rising. The value of regulated utility equity securities may tend to have an inverse relationship to the movement of interest rates. Certain utility companies have experienced full or partial deregulation in recent years. These utility companies are frequently more similar to industrial companies in that they are subject to greater competition and have been permitted by regulators to diversify outside of their original geographic regions and their traditional lines of business. These opportunities may permit certain utility companies to earn more than their traditional regulated rates of return. Some companies, however, may be forced to defend their core business and may be less profitable. In addition, natural disasters, terrorist attacks, government intervention or other factors may render a utility company’s equipment unusable or obsolete and negatively impact profitability. Among the risks that may affect utility companies are the following: risks of increases in fuel and other operating costs; the high cost of borrowing to finance capital construction during inflationary periods; restrictions on operations and increased costs and delays associated with compliance with environmental and nuclear safety regulations; and the difficulties involved in obtaining natural gas for resale or fuel for generating electricity at reasonable prices. Other risks include those related to the construction and operation of nuclear power plants, the effects of energy conservation and the effects of regulatory changes.
Risk Lose Money [Text]	rr_RiskLoseMoney	As with all investments, there are certain risks of investing in the Fund. Fund Shares will change in value, and you could lose money by investing in the Fund.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Non-Diversification Risk: As a “non-diversified” mutual fund, the Portfolio may hold a smaller number of portfolio securities than many other funds. To the extent the Portfolio invests in a relatively small number of issuers, a decline in the market value of a particular security held by the Portfolio may affect its value more than if it invested in a larger number of issuers. The value of the Portfolio’s shares may be more volatile than the values of shares of more diversified funds.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	FUND PERFORMANCE
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The Fund had not yet commenced operations as of the date of this Prospectus and therefore does not have any performance history. Once the Fund has completed a full calendar year of operations, a bar chart and table will be included that will provide some indication of the risks of investing in the Fund by showing the variability of the Fund’s returns based on net assets and comparing the Fund’s performance to a broad-based securities index. When available, the Fund will make updated performance information available by calling 1-866-787-2257 or visiting the Fund’s website: https://www.spdrs.com.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	The Fund had not yet commenced operations as of the date of this Prospectus and therefore does not have any performance history.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-866-787-2257
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	https://www.spdrs.com
SPDR(R) SSGA U.S. Sector Rotation ETF | SPDR(R) SSGA U.S. Sector Rotation ETF
Risk/Return:	rr_RiskReturnAbstract
Management fees	rr_ManagementFeesOverAssets		[1]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets		[1]
Other expenses	rr_OtherExpensesOverAssets		[1],[2]
Total annual Fund operating expenses	rr_ExpensesOverAssets		[1]
Year 1	rr_ExpenseExampleYear01
Year 3	rr_ExpenseExampleYear03

[1] [The Fund has adopted a Distribution and Service (12b-1) Plan pursuant to which payments of up to 0.25% of average daily net assets may be made; however, the Fund’s Board of Trustees has determined that no such payments will be made through the next twelve (12) months of operation.]

[2] Other expenses are based on estimated amounts for the current fiscal year.

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Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	SSGA Active Trust
Prospectus Date	rr_ProspectusDate	Dec. 17, 2017
Document Creation Date	dei_DocumentCreationDate	Mar. 17, 2016