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Janus Investment Fund

Janus Henderson Asia Equity Fund

(the “Fund”)

Supplement dated March 22, 2022

to Currently Effective Prospectuses

In connection with the change in portfolio management, effective immediately, the prospectuses for the Fund are amended as follows:

1.	The MSCI All Country Asia-Pacific ex‑Japan Index^SM is removed as the Fund’s secondary benchmark.

2.	Under “Principal Investment Strategies” in the Fund Summary section of the Fund’s prospectuses, the following paragraphs replace all corresponding paragraphs in their entirety:

The Fund pursues its investment objective by investing, under normal circumstances, at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities of Asian issuers (excluding Japanese issuers). An Asian issuer is generally considered to be any company that (i) is incorporated or has its principal business activities in an Asian country; (ii) is primarily listed on the trading market of an Asian country; or (iii) derives 50% or more of its revenue from, or has 50% or more of its assets in, one or more Asian countries. The Fund considers “Asian countries” to include, but not be limited to, Hong Kong, China, South Korea, Taiwan, Singapore, Malaysia, Thailand, Indonesia, Philippines, India, Vietnam, Pakistan, and Sri Lanka. The Fund may have significant exposure to emerging market countries.

The Fund generally invests in equity securities, which consist primarily of common stocks, preferred stocks, and depositary receipts, but may also include other types of instruments, such as equity-linked securities, real estate-related companies, and real estate investment trusts sponsored by Asian real estate companies. The Fund also invest in securities that cannot be offered for public resale unless registered under the applicable securities laws or that have a contractual restriction that prohibits or limits their resale (these are known as “restricted securities”). The Fund may invest in companies of any market capitalization. The Fund intends to diversify its investments across a number of different countries, including emerging market countries. The Fund may also invest in Chinese companies listed on U.S. and other exchanges structured as variable interest entities.

The Fund may invest in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may invest in derivatives such as futures, options, forward currency contracts, warrants, and swaps for various investment purposes, such as to gain exposure to a particular portion of the market or to manage or hedge portfolio risk.

The portfolio managers employ both a “top‑down” and “bottom‑up” approach to select investments for the Fund. The top‑down approach involves a macro analysis of factors that include a country’s economic growth profile, the stages of a country’s development, and trends in a country’s governance and regulatory framework. The bottom‑up analysis focuses on fundamental research and considers, among other factors, a company’s valuation, growth potential, competitive positioning, projected future earnings, cash flows, governance, and dividends. The Fund has the ability to invest more heavily in either growth or value securities depending on market conditions and the portfolio managers’ convictions. The Fund may engage in active and frequent trading to achieve its investment objective.

The Fund generally sells a stock when, in the portfolio managers’ opinion, there is a deterioration in the factors considered in selecting investments for the Fund, including changes in a country’s stage of development, governance, or regulatory framework. The Fund may also sell a stock when, in the portfolio managers’ opinion, a company’s fundamentals or a company’s revenue growth has slowed, or there has been changes in a company’s risk/reward potential.

3.	Under “Principal Investment Risks” in the Fund Summary section of the Fund’s prospectuses, the following risk factors replace all risk factors in their entirety:

Emerging Markets Risk. The risks of foreign investing are heightened when investing in emerging markets. Emerging market securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies. Information about emerging market companies, including financial information, may be less available or reliable and the Adviser’s ability to conduct due diligence with respect to such companies may be limited. Accordingly, these investments may be potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. There is a risk in developing countries that a current or future economic or political crisis could lead to price controls, forced mergers of companies, expropriation or confiscatory taxation, imposition or enforcement of foreign ownership limits, seizure, nationalization, sanctions or imposition of restrictions by various governmental entities on investment and trading, or creation of government monopolies, any of which may have a detrimental effect on the Fund’s investments. In addition, the taxation systems at the federal, regional, and local levels in developing or emerging market countries may be less transparent, inconsistently enforced, and subject to change. Emerging markets may be subject to a higher degree of corruption and fraud than developed markets and financial institutions and transaction counterparties may have less financial sophistication, creditworthiness, and/or resources than participants in developed markets. In addition, the Fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of the Fund’s investments. To the extent that the Fund invests a significant portion of its assets in the securities of emerging markets issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Additionally, foreign and emerging market risks, including but not limited to price controls, expropriation or confiscatory taxation, imposition or enforcement of foreign ownership limits, nationalization, and restrictions on repatriation of assets may be heightened to the extent the Fund invests in Chinese local market securities. Foreign and emerging market risks may also be heightened to the extent the Fund has exposure to Chinese issuers through variable interest entities, which subjects the Fund to the risks associated with the underlying Chinese issuer or operating company.

Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. The Fund’s investments in emerging market countries, if any, may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Market risk may affect a single issuer, industry, economic sector, or the market as a whole. Market risk may be magnified if certain social, political, economic, and other conditions and events (such as terrorism, conflicts, social unrest, natural disasters, epidemics and pandemics, including COVID‑19) adversely interrupt the global economy and financial markets.

Portfolio Management Risk. The Fund is an actively managed investment portfolio and is therefore subject to the risk that the investment strategies employed for the Fund may fail to produce the intended results. The Fund may underperform its benchmark index or other mutual funds with similar investment objectives.

Geographic Investment Risk. Because the Fund intends to focus its investments in a particular geographic region, the Fund’s performance is expected to be closely tied to various factors such as social, financial, economic, and political conditions within that region or country. Specifically, the Fund’s investments in Asian issuers increase the Fund’s exposure to the risks associated with volatile securities markets, adverse exchange rates, social, political and regulatory developments, and economic environmental events (such as natural disasters) which may be particular to Asian countries. Events that negatively affect the fiscal stability of Asian countries may cause the value of the Fund’s shares to decrease, in some cases

significantly. As a result, the Fund is likely to be more volatile than more geographically diverse funds. In addition, many of the economies of the Asian countries in which the Fund invests are interdependent, which may cause them to experience the impact of such events at the same time or may increase the possibility that conditions in one country or region might adversely impact the issuers of securities in a different country or region.

The economy of China differs, often unfavorably, from the U.S. economy in such respects as structure, general development, government involvement, wealth distribution, rate of inflation, growth rate, allocation of resources and capital reinvestment. The Chinese central government historically has exercised substantial control over virtually every sector of the Chinese economy through administrative regulation and/or state ownership. Actions of the Chinese government authorities continue to have a substantial effect on economic conditions in China. It is difficult for non‑Chinese investors to directly access securities in China because of investment and trading restrictions. These limitations and restrictions may impact the availability, liquidity, and pricing of certain securities.

Currency Risk. Currency risk is the risk that changes in the exchange rate between currencies will adversely affect the value (in U.S. dollar terms) of an investment. As long as the Fund holds a foreign security, its value will be affected by the value of the local currency relative to the U.S. dollar. When the Fund sells a foreign currency denominated security, its value may be worth less in U.S. dollars even if the security increases in value in its home country. U.S. dollar-denominated securities of foreign issuers may also be affected by currency risk, as the value of these securities may also be affected by changes in the issuer’s local currency.

Small- and Mid‑Sized Companies Risk. The Fund’s investments in securities issued by small- and mid‑sized companies, which can include smaller, start‑up companies offering emerging products or services, may involve greater risks than are customarily associated with larger, more established companies. Securities issued by small- and mid‑sized companies tend to be more volatile and somewhat more speculative than securities issued by larger or more established companies and may underperform as compared to the securities of larger or more established companies.

Industry and Sector Risk. Although the Fund does not concentrate its investments in specific industries or industry sectors, it may have a significant portion of its assets invested in securities of companies conducting similar business, or business within the same economic sector. Companies in the same industry or economic sector may be similarly affected by economic or market events, making the Fund more vulnerable to unfavorable developments than funds that invest more broadly. As the Fund’s portfolio becomes more concentrated, the Fund is less able to spread risk and potentially reduce the risk of loss and volatility. In addition, the Fund may be overweight or underweight in certain industries or sectors relative to its benchmark index, which may cause the Fund’s performance to be more or less sensitive to developments affecting those sectors.

Issuer Concentration Risk. The Fund’s portfolio may be comprised of a relatively small number of issuers in comparison to other funds. As a result, the Fund may be subject to greater risks than a fund that invests in a greater number of issuers. A change in the value of any single investment held by the Fund may affect the overall value of the Fund more than it would affect a fund that holds more investments. In particular, the Fund may be more susceptible to adverse developments affecting any single issuer held by the Fund and may be susceptible to greater losses because of these developments.

Growth Securities Risk. The Fund invests in companies that the portfolio managers believe have growth potential. Securities of companies perceived to be “growth” companies may be more volatile than other stocks and may involve special risks. If the portfolio managers’ perception of a company’s growth potential is not realized, the securities purchased may not perform as expected, reducing the Fund’s returns. In addition, because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “growth” stocks may perform differently from the market as a whole and other types of securities.

Value Investing Risk. The Fund may invest in value stocks. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers.

Depositary Receipts Risk. Depositary receipts are generally subject to the same sort of risks as direct investments in a foreign country, such as currency risk, market risk, and foreign exposure risk, because their values depend on the performance of a foreign security denominated in its home currency.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. REITs and REIT-like entities may have relatively small market capitalizations, which can increase the relative volatility of the market price for their securities. In addition, a REIT could fail to qualify for tax‑free pass-through of its income under the Internal Revenue Code of 1986, as amended, or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

Liquidity Risk. The Fund may invest in securities or instruments that do not trade actively or in large volumes, and may make investments that are less liquid than other investments. Also, the Fund may make investments that may become less liquid in response to market developments or adverse investor perceptions. Investments that are illiquid or that trade in lower volumes may be more difficult to value. When there is no willing buyer and investments cannot be readily sold at the desired time or price, the Fund may have to accept a lower price or may not be able to sell the security or instrument at all. Investments in foreign securities, particularly those of issuers located in emerging market countries, tend to have greater exposure to liquidity risk than domestic securities. In unusual market conditions, even normally liquid securities may be affected by a degree of liquidity risk (i.e., if the number and capacity of traditional market participants is reduced). An inability to sell one or more portfolio positions can adversely affect the Fund’s value or prevent the Fund from being able to take advantage of other investment opportunities.

Restricted Securities Risk. Securities that have limitations on their resale are referred to as “restricted securities.” Investments in restricted securities, including securities issued under Regulation S and Rule 144A, could have the effect of decreasing the Fund’s liquidity profile or preventing the Fund from disposing of them promptly at advantageous prices. Restricted securities may be less liquid than other investments because such securities may not always be readily sold in broad public markets and may have no active trading market. As a result, they may be difficult to value because market quotations may not be readily available.

Derivatives Risk. Derivatives can be volatile and involve risks in addition to the risks of the underlying referenced securities or asset. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. The Fund may use derivatives for hedging purposes. While hedging can reduce or eliminate losses, it can also reduce or eliminate gains or cause losses if the market moves in a manner different from that anticipated by the portfolio managers or if the cost of the derivative outweighs the benefit of the hedge.

Please retain this Supplement with your records.

Janus Investment Fund

Janus Henderson Absolute Return Income Opportunities Fund

(the “Fund”)

Supplement dated March 22, 2022

to Currently Effective Prospectuses

Effective on or about March 22, 2022, the Fund’s prospectuses are amended as follows:

1.	Under “Principal Investment Risks” in the Fund Summary section of the Fund’s prospectuses, the following risk factor is added:

Collateralized Debt Obligation Risk. The Fund may invest in collateralized debt obligations (“CDOs”), which include collateralized loan obligations (“CLOs”), collateralized bond obligations (“CBOs”), and other similarly structured securities. The risks of an investment in a CDO depend largely on the type of the collateral securities and the class of the CDO in which the Fund invests. In addition to the normal risks associated with fixed-income securities, CDOs carry additional risks including, but not limited to, the risk that: (i) distributions from collateral securities may not be adequate to make interest or other payments; (ii) the quality of the collateral may decline in value or default; (iii) the Fund may invest in CDOs that are subordinate to other classes; and (iv) the complex structure of the security may not be fully understood at the time of investment and may produce disputes with the issuer or unexpected investment results.

Please retain this Supplement with your records.

Risk/Return:

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Supplement to Prospectus [Text Block]

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Janus Investment Fund

Janus Henderson Asia Equity Fund

(the “Fund”)

Supplement dated March 22, 2022

to Currently Effective Prospectuses

In connection with the change in portfolio management, effective immediately, the prospectuses for the Fund are amended as follows:

1.	The MSCI All Country Asia-Pacific ex‑Japan Index^SM is removed as the Fund’s secondary benchmark.

2.	Under “Principal Investment Strategies” in the Fund Summary section of the Fund’s prospectuses, the following paragraphs replace all corresponding paragraphs in their entirety:

The Fund pursues its investment objective by investing, under normal circumstances, at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities of Asian issuers (excluding Japanese issuers). An Asian issuer is generally considered to be any company that (i) is incorporated or has its principal business activities in an Asian country; (ii) is primarily listed on the trading market of an Asian country; or (iii) derives 50% or more of its revenue from, or has 50% or more of its assets in, one or more Asian countries. The Fund considers “Asian countries” to include, but not be limited to, Hong Kong, China, South Korea, Taiwan, Singapore, Malaysia, Thailand, Indonesia, Philippines, India, Vietnam, Pakistan, and Sri Lanka. The Fund may have significant exposure to emerging market countries.

The Fund generally invests in equity securities, which consist primarily of common stocks, preferred stocks, and depositary receipts, but may also include other types of instruments, such as equity-linked securities, real estate-related companies, and real estate investment trusts sponsored by Asian real estate companies. The Fund also invest in securities that cannot be offered for public resale unless registered under the applicable securities laws or that have a contractual restriction that prohibits or limits their resale (these are known as “restricted securities”). The Fund may invest in companies of any market capitalization. The Fund intends to diversify its investments across a number of different countries, including emerging market countries. The Fund may also invest in Chinese companies listed on U.S. and other exchanges structured as variable interest entities.

The Fund may invest in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may invest in derivatives such as futures, options, forward currency contracts, warrants, and swaps for various investment purposes, such as to gain exposure to a particular portion of the market or to manage or hedge portfolio risk.

The portfolio managers employ both a “top‑down” and “bottom‑up” approach to select investments for the Fund. The top‑down approach involves a macro analysis of factors that include a country’s economic growth profile, the stages of a country’s development, and trends in a country’s governance and regulatory framework. The bottom‑up analysis focuses on fundamental research and considers, among other factors, a company’s valuation, growth potential, competitive positioning, projected future earnings, cash flows, governance, and dividends. The Fund has the ability to invest more heavily in either growth or value securities depending on market conditions and the portfolio managers’ convictions. The Fund may engage in active and frequent trading to achieve its investment objective.

The Fund generally sells a stock when, in the portfolio managers’ opinion, there is a deterioration in the factors considered in selecting investments for the Fund, including changes in a country’s stage of development, governance, or regulatory framework. The Fund may also sell a stock when, in the portfolio managers’ opinion, a company’s fundamentals or a company’s revenue growth has slowed, or there has been changes in a company’s risk/reward potential.

3.	Under “Principal Investment Risks” in the Fund Summary section of the Fund’s prospectuses, the following risk factors replace all risk factors in their entirety: