Summary Prospectus dated March 1, 2018

Eaton Vance Floating-Rate Fund

Class /Ticker     Advisers / EABLX     A / EVBLX     B / EBBLX     C / ECBLX     I / EIBLX     R6 / ESBLX

This Summary Prospectus is designed to provide investors with key fund information in a clear and concise format. Before you invest, you may want to review the Fund’s Prospectus and Statement of Additional Information, which contain more information about the Fund and its risks. The Fund’s Prospectus and Statement of Additional Information, both dated March 1, 2018, as may be amended or supplemented, are incorporated by reference into this Summary Prospectus. For free paper or electronic copies of the Fund’s Prospectus, Statement of Additional Information, and other information about the Fund, go to http://www.eatonvance.com/funddocuments, email a request to contact@eatonvance.com, call 1-800-262-1122, or ask any financial advisor, bank, or broker-dealer who offers shares of the Fund. Unless otherwise noted, page number references refer to the current Prospectus for this Fund.

Investment Objective

The Fund’s investment objective is to provide a high level of current income.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. Investors may also pay commissions or other fees to their financial intermediary when they buy and hold shares of the Fund, which are not reflected below. You may qualify for a reduced sales charge on purchases of Class A shares if you invest, or agree to invest over a 13-month period, at least $100,000 in Eaton Vance funds. Certain financial intermediaries also may offer variations in Fund sales charges to their customers as described in Appendix A – Financial Intermediary Sales Charge Variations in the Fund's Prospectus. More information about these and other discounts is available from your financial intermediary and in Sales Charges beginning on page 35 of the Fund's Prospectus and page 24 of the Fund’s Statement of Additional Information.

Shareholder Fees (fees paid directly from your investment)	Advisers Class	Class A	Class B	Class C	Class I	Class R6
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	None	2.25%	None	None	None	None
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of net asset value at purchase or redemption)	None	None	5.00%	1.00%	None	None

Annual Fund Operating Expenses (expenses you pay each year as a percentage of the value of your investment)(1)	Advisers Class	Class A	Class B	Class C	Class I	Class R6
Management Fees	0.64%	0.64%	0.64%	0.64%	0.64%	0.64%
Distribution and Service (12b-1) Fees	0.25%	0.25%	1.00%	1.00%	None	None
Other Expenses	0.15%	0.15%	0.15%	0.15%	0.15%	0.09%
Net Annual Fund Operating Expenses	1.04%	1.04%	1.79%	1.79%	0.79%	0.73%

⁽¹⁾ Expenses in the table above and the Example below reflect the expenses of the Fund and the Eaton Vance Floating Rate Portfolio (the “Portfolio”), the Fund’s master Portfolio.

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 redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the operating expenses remain the same and that any expense reimbursement arrangement remains in place for the contractual period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

	Expenses with Redemption				Expenses without Redemption
	1 Year	3 Years	5 Years	10 Years	1 Year	3 Years	5 Years	10 Years
Advisers Class shares	$106	$331	$574	$1,271	$106	$331	$574	$1,271
Class A shares	$329	$548	$786	$1,467	$329	$548	$786	$1,467
Class B shares	$682	$963	$1,170	$1,908	$182	$563	$970	$1,908
Class C shares	$282	$563	$970	$2,105	$182	$563	$970	$2,105
Class I shares	$81	$252	$439	$978	$81	$252	$439	$978
Class R6 shares	$75	$233	$406	$906	$75	$233	$406	$906

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” the 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. During the most recent fiscal year, the Portfolio's portfolio turnover rate was 42% of the average value of its portfolio.

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its total assets in income producing floating rate loans and other floating rate debt securities. The Fund invests primarily in senior floating rate loans of domestic and foreign borrowers (“Senior Loans”). Senior Loans typically are secured with specific collateral and have a claim on the assets and/or stock of the borrower that is senior to subordinated debtholders and stockholders of the borrower. Loans usually are of below investment grade quality and have below investment grade credit ratings, which ratings are associated with securities having high risk, speculative characteristics (sometimes referred to as “junk”).

The Fund may also invest in secured and unsecured subordinated loans, second lien loans and subordinated bridge loans (“Junior Loans”), other floating rate debt securities, fixed-income debt obligations and money market instruments. Other floating rate debt securities, fixed-income debt securities and money market instruments may include: bonds, notes and debentures issued by corporations; debt securities issued or guaranteed by the U.S. government or one of its agencies or instrumentalities; and commercial paper. Money market instruments with a remaining maturity of less than 60 days are deemed floating rate debt securities. Senior Loans and Junior Loans are referred to together herein as “loans.”

The Fund may invest up to 25% of its total assets in foreign Senior Loans. Foreign Senior Loans must be denominated in U.S. dollars, euros, British pounds, Swiss francs, Canadian dollars, or Australian dollars. The Fund may engage in derivative transactions (such as futures contracts and options thereon, foreign currency exchange contracts and other currency hedging strategies, and interest rate swaps) to seek to hedge against fluctuations in currency exchange rates and interest rates. There is no stated limit on the Fund’s use of derivatives.

The investment adviser seeks to maintain broad borrower and industry diversification among the Fund’s loans. When selecting loans, the investment adviser seeks to implement a systematic risk-weighted approach that utilizes fundamental analysis of risk/return characteristics. Loans may be sold, if in the opinion of the investment adviser, the risk-return profile deteriorates or to pursue more attractive investment opportunities. In managing the Fund, the investment adviser seeks to invest in a portfolio of loans that it believes will be less volatile over time than the general loan market. Preservation of capital is considered when consistent with the Fund’s investment objective.

The Fund currently invests its assets in the Portfolio, a separate registered investment company with the same investment objective and policies as the Fund.

Eaton Vance Floating-Rate Fund 2 Summary Prospectus dated March 1, 2018

Principal Risks

Market Risk. The value of investments held by the Fund may increase or decrease in response to economic, political and financial events (whether real, expected or perceived) in the U.S. and global markets. The frequency and magnitude of such changes in value cannot be predicted. Certain securities and other investments held by the Fund may experience increased volatility, illiquidity, or other potentially adverse effects in reaction to changing market conditions. Actions taken by the U.S. Federal Reserve or foreign central banks to stimulate or stabilize economic growth, such as decreases or increases in short-term interest rates, could cause high volatility in markets. No active trading market may exist for certain investments, which may impair the ability of the Fund to sell or to realize the current valuation of such investments in the event of the need to liquidate such assets. Fixed-income markets may experience periods of relatively high volatility in an environment where U.S. treasury yields are rising.

Credit Risk. Investments in loans and other debt obligations (referred to below as “debt instruments”) are subject to the risk of non-payment of scheduled principal and interest. Changes in economic conditions or other circumstances may reduce the capacity of the party obligated to make principal and interest payments on such instruments and may lead to defaults. Such non-payments and defaults may reduce the value of Fund shares and income distributions. The value of debt instruments also may decline because of concerns about the issuer’s ability to make principal and interest payments. In addition, the credit ratings of debt instruments may be lowered if the financial condition of the party obligated to make payments with respect to such instruments deteriorates. In the event of bankruptcy of the issuer of a debt instrument, the Fund could experience delays or limitations with respect to its ability to realize the benefits of any collateral securing the instrument. In order to enforce its rights in the event of a default, bankruptcy or similar situation, the Fund may be required to retain legal or similar counsel, which may increase the Fund’s operating expenses and adversely affect net asset value. Due to their lower place in the borrower’s capital structure, Junior Loans involve a higher degree of overall risk than Senior Loans of the same borrower.

Additional Risks of Loans. Loans are traded in a private, unregulated inter-dealer or inter-bank resale market and are generally subject to contractual restrictions that must be satisfied before a loan can be bought or sold. These restrictions may impede the Fund’s ability to buy or sell loans (thus affecting their liquidity) and may negatively impact the transaction price. See also “Market Risk” above. It also may take longer than seven days for transactions in loans to settle. Due to the possibility of an extended loan settlement process, the Fund may hold cash, sell investments or temporarily borrow from banks or other lenders to meet short-term liquidity needs, such as to satisfy redemption requests from Fund shareholders. Loans may be structured such that they are not securities under securities law, and in the event of fraud or misrepresentation by a borrower, lenders may not have the protection of the anti-fraud provisions of the federal securities laws. Loans are also subject to risks associated with other types of income investments as described herein.

Lower Rated Investments Risk. Investments rated below investment grade and comparable unrated investments (sometimes referred to as “junk”) have speculative characteristics because of the credit risk associated with their issuers. Changes in economic conditions or other circumstances typically have a greater effect on the ability of issuers of lower rated investments to make principal and interest payments than they do on issuers of higher rated investments. An economic downturn generally leads to a higher non-payment rate, and a lower rated investment may lose significant value before a default occurs. Lower rated investments typically are subject to greater price volatility and illiquidity than higher rated investments.

Interest Rate Risk. In general, the value of income securities will fluctuate based on changes in interest rates. The value of these securities is likely to increase when interest rates fall and decline when interest rates rise. Generally, securities with longer maturities are more sensitive to changes in interest rates than shorter maturity securities, causing them to be more volatile. Conversely, fixed income securities with shorter maturities will be less volatile but generally provide lower returns than fixed income securities with longer maturities. The impact of interest rate changes on the value of floating rate investments is typically reduced by periodic interest rate resets. In a rising interest rate environment, the maturities of income securities that have the ability to be prepaid or called by the issuer may be extended. In a declining interest rate environment, the proceeds from prepaid or maturing instruments may have to be reinvested at a lower interest rate.

Foreign Investment Risk. Foreign investments can be adversely affected by political, economic and market developments abroad, including the imposition of economic and other sanctions by the United States or another country. Foreign markets may be smaller, less liquid and more volatile than the major markets in the United States, and as a result, Fund share values may be more volatile. Trading in foreign markets typically involves higher expense than trading in the United States. The Fund may have difficulties enforcing its legal or contractual rights in a foreign country.

Currency Risk. Exchange rates for currencies fluctuate daily. The value of foreign investments may be affected favorably or unfavorably by changes in currency exchange rates in relation to the U.S. dollar. Currency markets generally are not as regulated as securities markets and currency transactions are subject to settlement, custodial and other operational risks.

Eaton Vance Floating-Rate Fund 3 Summary Prospectus dated March 1, 2018

U.S. Government Securities Risk. Although certain U.S. Government-sponsored agencies (such as the Federal Home Loan Mortgage Corporation and the Federal National Mortgage Association) may be chartered or sponsored by acts of Congress, their securities are neither issued nor guaranteed by the U.S. Treasury. U.S. Treasury securities generally have a lower return than other obligations because of their higher credit quality and market liquidity.

Money Market Instrument Risk. Money market instruments may be adversely affected by market and economic events, such as a sharp rise in prevailing short-term interest rates; adverse developments in the banking industry, which issues or guarantees many money market instruments; adverse economic, political or other developments affecting issuers of money market instruments; changes in the credit quality of issuers; and default by a counterparty.

Derivatives Risk. The Fund’s exposure to derivatives involves risks different from, or possibly greater than, the risks associated with investing directly in securities and other investments. The use of derivatives can lead to losses because of adverse movements in the price or value of the asset, index, rate or instrument underlying a derivative, due to failure of a counterparty or due to tax or regulatory constraints. Derivatives may create leverage in the Fund, which represents a non-cash exposure to the underlying asset, index, rate or instrument. Leverage can increase both the risk and return potential of the Fund. Derivatives risk may be more significant when derivatives are used to enhance return or as a substitute for a cash investment position, rather than solely to hedge the risk of a position held by the Fund. Use of derivatives involves the exercise of specialized skill and judgment, and a transaction may be unsuccessful in whole or in part because of market behavior or unexpected events. Changes in the value of a derivative (including one used for hedging) may not correlate perfectly with the underlying asset, rate, index or instrument. Derivative instruments traded in over-the-counter markets may be difficult to value, may be illiquid, and may be subject to wide swings in valuation caused by changes in the value of the underlying instrument. If a derivative’s counterparty is unable to honor its commitments, the value of Fund shares may decline and the Fund could experience delays in the return of collateral or other assets held by the counterparty. The loss on derivative transactions may substantially exceed the initial investment, particularly when there is no stated limit on the Fund’s use of derivatives. A derivative investment also involves the risks relating to the asset, index, rate or instrument underlying the investment.

Risks Associated with Active Management. The success of the Fund’s investment strategy depends on portfolio management’s successful application of analytical skills and investment judgment. Active management involves subjective decisions.

General Fund Investing Risks. The Fund is not a complete investment program and there is no guarantee that the Fund will achieve its investment objective. It is possible to lose money by investing in the Fund. The Fund is designed to be a long-term investment vehicle and is not suited for short-term trading. Investors in the Fund should have a long-term investment perspective and be able to tolerate potentially sharp declines in value. Purchase and redemption activities by Fund shareholders may impact the management of the Fund and its ability to achieve its investment objective(s). In addition, the redemption by one or more large shareholders or groups of shareholders of their holdings in the Fund could have an adverse impact on the remaining shareholders in the Fund. An investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Eaton Vance Floating-Rate Fund 4 Summary Prospectus dated March 1, 2018

Performance

The following bar chart and table provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and how the Fund’s average annual returns over time compare with those of a broad-based securities market index. The returns in the bar chart are for Class A shares and do not reflect a sales charge. If the sales charge was reflected, the returns would be lower. Past performance (both before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated Fund performance information can be obtained by visiting www.eatonvance.com.

For the ten years ended December 31, 2017, the highest quarterly total return for Class A was 18.77% for the quarter ended June 30, 2009, and the lowest quarterly return was -24.28% for the quarter ended December 31, 2008. For the 30 days ended October 31, 2017, the SEC yield for Advisers Class shares was 3.49%, for Class A shares was 3.42%, for Class B shares was 2.74%, for Class C shares was 2.74%, for Class I shares was 3.74% and for Class R6 shares was 3.79%. Current yield information can be obtained by visiting www.eatonvance.com.

Average Annual Total Return as of December 31, 2017	One Year	Five Years	Ten Years
Advisers Class Return Before Taxes	4.09%	3.50%	3.83%
Class A Return Before Taxes	1.77%	3.03%	3.60%
Class A Return After Taxes on Distributions	0.21%	1.40%	1.99%
Class A Return After Taxes on Distributions and the Sale of Class A Shares	0.99%	1.56%	2.09%
Class B Return Before Taxes	-1.57%	2.39%	3.07%
Class C Return Before Taxes	2.32%	2.73%	3.07%
Class I Return Before Taxes	4.47%	3.78%	4.10%
Class R6 Return Before Taxes	4.41%	3.79%	4.10%
S&P/LSTA Leveraged Loan Index (reflects no deduction for fees, expenses or taxes)	4.12%	4.03%	4.85%

These returns reflect the maximum sales charge for Class A (2.25%) and any applicable contingent deferred sales charge (“CDSC”) for Class B and Class C. The Class R6 performance shown above for the period prior to December 1, 2016 (commencement of operations) is the performance of Class I shares at net asset value without adjustment for any differences in the expenses of the two classes. If adjusted for such differences, returns would be different. Investors cannot invest directly in an Index.

After-tax returns are calculated using the highest historical individual federal income tax rate and do not reflect the impact of state and local taxes. Actual after-tax returns depend on a shareholder’s tax situation and the actual characterization of distributions, and may differ from those shown. After-tax returns are not relevant for shareholders who hold Fund shares in tax-deferred accounts or to shares held by non-taxable entities. After-tax returns for other Classes of shares will vary from the after-tax returns presented for Class A shares. Return After Taxes on Distributions for a period may be the same as Return Before Taxes for that period because no taxable distributions were made during that period. Also, Return After Taxes on Distributions and Sale of Fund Shares for a period may be greater than or equal to Return After Taxes on Distributions for the same period because of losses realized on the sale of Fund shares.

Management

Investment Adviser. Boston Management and Research (“BMR”).

Portfolio Managers

Scott H. Page, Vice President of BMR, has managed the Portfolio since February 2001.

Craig P. Russ, Vice President of BMR, has managed the Portfolio since November 2007.

Eaton Vance Floating-Rate Fund 5 Summary Prospectus dated March 1, 2018

Purchase and Sale of Fund Shares

You may purchase, redeem or exchange Fund shares on any business day, which is any day the New York Stock Exchange is open for business. Class B shares are only available for purchase upon exchange from another Eaton Vance fund or through reinvestment of distributions. You may purchase, redeem or exchange Fund shares either through your financial intermediary or (except for purchases of Class C shares by accounts with no specified financial intermediary) directly from the Fund either by writing to the Fund, P.O. Box 9653, Providence, RI 02940-9653, or by calling 1-800-262-1122. The minimum initial purchase or exchange into the Fund is $1,000 for Advisers Class, Class A, Class B and Class C, $250,000 for Class I and $1,000,000 for Class R6 (waived in certain circumstances). There is no minimum for subsequent investments.

Tax Information

If your shares are held in a taxable account, the Fund’s distributions will be taxed to you as ordinary income and/or capital gains, unless you are exempt from taxation. If your shares are held in a tax-advantaged account, you will generally be taxed only upon withdrawals from the account.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase the Fund’s shares through a broker-dealer or other financial intermediary (such as a bank) (collectively, “financial intermediaries”), the Fund, its principal underwriter and its affiliates may pay the financial intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the financial intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary’s website for more information.

4342 3.1.18 © 2018 Eaton Vance Management

Eaton Vance Floating-Rate Fund 6 Summary Prospectus dated March 1, 2018