Document and Entity Information	Total
Document And Entity Information
Document Type	497
Document Period End Date	Dec. 31, 2017
Registrant Name	Investment Managers Series Trust
Central Index Key	0001318342
Amendment Flag	false
Document Creation Date	Jun. 14, 2018
Document Effective Date	Jun. 14, 2018
Prospectus Date	May 01, 2018

dei_DocumentType

497

dei_EntityRegistrantName

Investment Managers Series Trust

Amendment Flag

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false

Document Effective Date

dei_DocumentEffectiveDate

Jun. 14, 2018

Risk/Return [Heading]

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SUMMARY SECTION

LS Theta Fund

Objective, Primary [Text Block]

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The investment objective of the LS Theta Fund (the “Fund”) is to seek to generate current income with a low correlation to the risks and returns of major market indices.

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Operating Expenses Caption [Text]

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Annual Fund Operating Expenses
(expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover, Rate

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3.00%

Expense Example Narrative [Text Block]

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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 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 Narrative [Text Block]

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Under normal market conditions, the Fund seeks to achieve its investment objective by selling listed short-term put options to generate income to the Fund while also purchasing intermediate-term put options for hedging purposes. The put options sold and purchased by the Fund will primarily be on the S&P 500 Index. If the purchaser of a put option exercises the option, the seller of the put option is obligated to buy the underlying instrument at a specified exercise price. Put options are among the types of instruments commonly referred to as derivatives. The sale of put options generates income for the Fund through the receipt of cash (i.e., premiums), but exposes it to the risk of declines in the value of the underlying assets below the option strike price that are in excess of the income collected. In an effort to protect against significant declines in the value of the underlying assets below the strike price of an option, the Fund will purchase long put options. A long put option gives the purchaser of the option, upon payment of a premium, the right to sell a specified quantity of an underlying asset at a fixed exercise price over a defined period of time.

The Fund’s sale and purchase of put options is designed to generate a positive return in rising and flat equity markets, and may generate a positive return in equity markets that are modestly declining, assuming the net premiums collected from the options written and purchased exceeds the net cost to close the position. In an effort to limit losses in declining equity markets, the Fund may reduce its sale of put options and/or purchase put options with strike prices closer to the strike prices of the put options sold.

The Fund focuses primarily on equity index options which offer both European settlement (i.e., options can only be exercised at their expiration date) and cash settlement (i.e., options carry an obligation by their seller to pay the difference between their strike price and their settlement value instead of allowing the seller to take delivery of securities). However, the Fund reserves the right to use options which offer American settlement (i.e., options can be exercised any time prior to their expiration date) which may allow delivery of underlying stock. While the Fund’s adviser expects that the Fund will primarily write short-term put options (i.e., options that expire in less than 3 weeks) and purchase intermediate-term put options (i.e., options that expire in 3-6 weeks), the Fund reserves the right to utilize options of various expirations. The Fund writes put options with shorter expirations than the put options purchased in an effort to collect more premiums over time from the short-term puts sold than premiums paid on the longer-term puts purchased.

The potential returns of the Fund are generally limited to the amount of cash (premiums) the Fund receives when selling put options, net of any cash (premiums) paid by the Fund to purchase long put options, plus the returns of the fixed income securities in which the Fund invests. The Fund’s sale and purchase of put options may result in the generation of positive returns for the Fund; however, the loss potential if the strategy is not effective may be greater than the profit potential. The Fund may lose significantly more than the premiums it receives in highly volatile market conditions.

The Fund may also invest in fixed income securities to cover the put options it sells and/or to seek its investment objective. The fixed income securities in which the Fund invests may include government and agency debt obligations and investment grade corporate debt obligations (with an average weighted maturity of less than 5 years). The Fund may invest in fixed income securities issued by companies of any market capitalization. The Fund’s adviser evaluates investments in fixed income securities based on credit quality, coupon, allocation needs and diversification requirements.

The Fund will segregate cash and/or other liquid assets in an amount equal to the Fund’s obligations under each put option sold by the Fund so that each option sold will be secured, or “covered”. The Fund’s adviser intends to limit the use of leverage by ensuring that the Fund’s potential obligations from the put options sold will not exceed the Fund’s total net assets.

The Fund’s adviser employs a disciplined portfolio construction process that relies on guidelines to govern capital allocations based on a quantitative methodology designed by the Fund’s adviser to measure the perceived risk of the broad U.S. equity market. In making this determination, the Fund’s adviser considers various factors including but not limited to the overall volatility (rate of change) in the markets. The Fund’s adviser bases allocation decisions on a combination of quantitative risk measures and a qualitative assessment of potential risk/reward scenarios, with the ultimate goals of dampening volatility in the Fund’s portfolio and maintaining adequate portfolio diversification while achieving the Fund’s targeted return potential. The Fund’s adviser evaluates the metrics associated with the valuation of options, including volatility, time to expiration and the relationship of the exercise price to the prevailing market price of the underlying instrument. There can be no guarantee that the strategy of the Fund’s adviser will be successful in this regard. During market conditions in which market volatility rises, the price of options could rise, which, in turn, could have a detrimental effect on the Fund’s performance and achieving its targeted return potential.

Risk Narrative [Text Block]

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Risk is inherent in all investing and you could lose some or the entire principal amount invested in the Fund. A summary description of certain principal risks of investing in the Fund is set forth below. Before you decide whether to invest in the Fund, carefully consider these risk factors associated with investing in the Fund, which may cause investors to lose money. There can be no assurance that the Fund will achieve its investment objective.

•

Equity Risk. The value of certain put options sold by the Fund is based on the value of the stocks underlying such options. Accordingly, the Fund is exposed to equity risk. The value of equity securities may fall due to general market and economic conditions, perceptions regarding the industries in which the issuers participate, or factors relating to specific companies.

•

ETF Risk. The value of certain put options sold by the Fund is based on the value of the ETFs underlying such options. Accordingly, the Fund is exposed to ETF risk. ETFs typically trade on securities exchanges and their shares may, at times, trade at a premium or discount to their net asset values. An ETF may not replicate exactly the performance of the benchmark index it seeks to track for a number of reasons, including transaction costs incurred by the ETF, the temporary unavailability of certain index securities in the secondary market or discrepancies between the ETF and the index with respect to the weighting of securities or the number of securities held.

	•	Fixed Income Securities (Bond) Risk. The prices of fixed income securities respond to economic developments, particularly interest rate changes, as well as to changes in an issuer’s credit rating or market perceptions about the creditworthiness of an issuer. Generally fixed income securities decrease in value if interest rates rise and increase in value if interest rates fall, and longer-term and lower rated securities are more volatile than shorter-term and higher rated securities.

	•	Government-Sponsored Entities Risk. The Fund’s investment in U.S. government obligations may include securities issued or guaranteed as to principal and interest by the U.S. government, or its agencies or instrumentalities. Payment of principal and interest on U.S. government obligations may be backed by the full faith and credit of the United States or may be backed solely by the issuing or guaranteeing agency or instrumentality itself. There can be no assurance that the U.S. government would provide financial support to its agencies or instrumentalities (including government-sponsored enterprises) when it is not obligated to do so.

•

Interest Rate Risk. Generally fixed income securities decrease in value if interest rates rise and increase in value if interest rates fall, with longer-term securities being more sensitive than shorter-term securities. For example, the price of a security with a three-year duration would be expected to drop by approximately 3% in response to a 1% increase in interest rates. Generally, the longer the maturity and duration of a bond or fixed rate loan, the more sensitive it is to this risk. Falling interest rates also create the potential for a decline in the Fund’s income. Changes in governmental policy, rising inflation rates, and general economic developments, among other factors, could cause interest rates to increase and could have a substantial and immediate effect on the values of the Fund’s investments. In addition, a potential rise in interest rates may result in periods of volatility and increased redemptions that might require the Fund to liquidate portfolio securities at disadvantageous prices and times.

•

Large-Cap Company Risk. The value of certain put options sold by the Fund is based on the value of the stocks issued by large sized companies. Accordingly, the Fund is exposed to large-capitalization company risk. Larger, more established companies may be unable to attain the high growth rates of successful, smaller companies during periods of economic expansion.

•

Management and Strategy Risk. The value of your investment depends on the judgment of the Adviser about the quality, relative yield, value or market trends affecting a particular security, industry, sector or region, which may prove to be incorrect.

•

Market Risk. The market price of a security or instrument may decline, sometimes rapidly or unpredictably, due to general market conditions that are not specifically related to a particular company, such as real or perceived adverse economic or political conditions throughout the world, changes in the general outlook for corporate earnings, changes in interest or currency rates or adverse investor sentiment generally. The market value of a security or instrument also may decline because of factors that affect a particular industry or industries, such as labor shortages or increased production costs and competitive conditions within an industry.

•

Put Options Risk. Purchasing and writing put options are highly specialized activities and entail greater than ordinary investment risks. The Fund may not fully benefit from or may lose money on an option if changes in its value do not correspond as anticipated to changes in the value of the underlying securities. The risk associated with selling a put option is that the market value of the underlying security could decrease and the option could be exercised, obligating the seller of the put option to settle the transaction at an exercise price that is higher than the prevailing market price. Ownership of options involves the payment of premiums, which may adversely affect the Fund’s performance. To the extent that the Fund invests in over-the-counter options, the Fund may be exposed to counterparty risk. A long put option gives the purchaser of the option the right to sell a specified quantity of an underlying asset at a fixed exercise price over a defined period of time. Purchased put options may expire worthless and the Fund would lose the premium it paid for the option.

•

Sector Focus Risk. The Fund may invest a larger portion of its assets in one or more sectors than many other mutual funds, and thus will be more susceptible to negative events affecting those sectors. For example, as of December 31, 2017, the Fund invested significant amounts of its total assets in the financial sector. Companies in the financial sector may be adversely affected by many factors, including among others, fluctuations in interest rates, government regulation, economic conditions, credit rating downgrades, and decreased liquidity in the credit markets. The impact of more stringent capital requirements or future regulation on any individual financial company or on the sector as a whole cannot be predicted.

•

Small-Cap and Mid-Cap Company Risk. The value of certain put options sold by the Fund is based on the value of the stocks issued by small and medium sized companies. Accordingly, the Fund is exposed to small-capitalization and mid-capitalization company risk. The securities of small-capitalization and mid-capitalization companies may be subject to more abrupt or erratic market movements and may have lower trading volumes or more erratic trading than securities of larger, more established companies or market averages in general. In addition, such companies typically are more likely to be adversely affected than large capitalization companies by changes in earning results, business prospects, investor expectations or poor economic or market conditions.

Bar Chart and Performance Table [Heading]

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Performance

Performance Information Illustrates Variability of Returns [Text]

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The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year for Institutional Class shares and by showing how the average annual total returns of each class of the Fund compare with the average annual total returns of two broad-based market indexes.

Performance Availability Website Address [Text]

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www.lsthetafund.com

Bar Chart [Heading]

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Calendar-Year Total Return (before taxes) – Institutional Class Shares

For each calendar year at NAV

Performance Table Heading

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Average Annual Total Returns

(for Periods Ended December 31, 2017)

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table One Class of after Tax Shown [Text]

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After-tax returns are shown for Institutional Class shares only and after-tax returns for classes other than Institutional Class shares will vary from returns shown for Institutional Class shares.

Risk Return Abstract

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Wire fee

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$ 20

Retirement account fees (annual maintenance fee)

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$ 15

Distribution (Rule 12b-1) fees

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0.25%

Interest expense