May 1, 2024

Mid Cap Growth Portfolio

SUMMARY PROSPECTUS

Class S

The Fund is offered to certain life insurance companies to serve as an investment vehicle for premiums paid under their variable annuity and variable life insurance contracts (each, a “variable contract”) and to certain qualified pension and other retirement plans (each, a “qualified plan”). Before you invest, you may want to review the Fund’s prospectus, which contains more information about the Fund and its risks. You can find the Fund’s prospectus, reports to shareholders, and other information about the Fund (including the Fund’s SAI) online at http://www.nb.com/amtportfolios/s. You can also get this information at no cost by calling 800-877-9700 or by sending an e-mail request to fundinfo@nb.com. You can also get this information from your investment provider or any investment provider authorized to sell the Fund’s shares. The Fund’s prospectus and SAI, each dated May 1, 2024 (as each may be amended or supplemented), are incorporated herein by reference.

GOAL

The Fund seeks growth of capital.

Fees and Expenses

These tables describe the fees and expenses that you may pay if you buy, hold or sell shares of the Fund. These tables do not reflect any fees and expenses charged by your insurance company under your variable contract or by your qualified plan. If the tables did reflect such fees and expenses, the overall expenses would be higher than those shown. Please refer to the prospectus for your variable contract or your qualified plan documentation for information on their separate fees and expenses.

Expense Example

The expense example can help you compare costs among mutual funds. The example assumes that you invested $10,000 for the periods shown, that you redeemed all of your shares at the end of those periods, that the Fund earned a hypothetical 5% total return each year, and that the Fund’s expenses were those in the table. Actual performance and expenses may be higher or lower.

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. These costs, which are not reflected in annual operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 105% of the average value of its portfolio.

Principal Investment Strategies

To pursue its goal, the Fund normally invests at least 80% of its net assets in common stocks of mid-capitalization companies, which it defines as those with a market capitalization within the market capitalization range of the Russell Midcap® Index at the time of initial purchase. Although the Fund invests primarily in domestic securities, it may also invest in securities of foreign companies.

The Fund’s strategy utilizes a qualitative, bottom-up research driven approach to identify companies that the Portfolio Managers believe have catalysts for growth which are underappreciated by the market. The Portfolio Managers seek to invest in

underappreciated companies with the following characteristics: durable and potentially unique business models and/or proficient management capable of advancing the development of and/or strengthening of sustainable and consistent revenue growth, cash flow growth, earnings growth and/or overall balance sheet strength. Such catalysts may include a new technology, product or service, a regulatory update, market share gains, cyclical inflections (e.g. companies whose returns are driven by macro-economic factors), corporate restructurings or self-help initiatives (e.g. internal operating efforts to increase company efficiencies). The Portfolio Managers may also invest in anticipation of a catalyst.

In analyzing catalysts, the Portfolio Managers evaluate each catalyst’s uniqueness, timing, growth potential and sustainability, as well as assessing execution risks, competitive barriers and threats. The Portfolio Managers are also attempting to exploit market inefficiencies that potentially may exist within the small-to-mid-capitalization market, due to the number of companies that comprise the investable universe and the limited amount of available research that exists for some of those companies. Investable companies emerging from the Portfolio Manager’s bottom-up fundamental, qualitative and valuation analysis fall into the following investment classifications:

Core investments: are typically more mature companies, engaged with, and participating in, compelling secular growth trends, that the Portfolio Managers believe offer a demonstrated history of consistent execution and results. These tend to represent multi-year holdings of the strategy.

Turn investments: represent holdings in a wide range of corporate development and maturity stages and are generally driven by what the Portfolio Managers believe to be a distinct developing catalyst, such as a new product or service, market share gains or internal corporate self-help opportunities to improve operating efficiencies.

Tactical investments: represent holdings with a shorter-term investment horizon due to catalysts the Portfolio Managers believe are typically associated with cyclical trends and opportunities, a disconnect with market expectations providing an opportunity on valuation or a new product, or financial or regulatory developments that could have a material impact on the company.

Tactical investments have the potential to grow into Turn investments, while compelling Turn investments will ideally develop into Core investments.

The Fund seeks to reduce risk by diversifying among many companies, sectors and industries. At times, the Portfolio Managers may emphasize certain sectors that they believe will benefit from market or economic trends.

The Portfolio Managers constantly monitor their holdings and are focused on maintaining what they believe is an appropriate and attractive risk/reward balance with a disciplined sell process that acts quickly and dispassionately to address both positive and negative outcomes. A position is typically trimmed or exited for the following reasons: to harvest gains from significant short-term price appreciation, the positive realization of a catalyst, the achievement of a price target or elevated valuations, identification of a better idea, to minimize potential risks, to address an absence of near-term drivers or catalysts, a significant deterioration of fundamentals, a change in management or operating strategy or the failure of a catalyst to develop.

The Fund will not change its strategy of normally investing at least 80% of its net assets in mid-capitalization companies, without providing shareholders at least 60 days’ notice. This test is applied at the time the Fund invests; later percentage changes caused by a change in Fund assets, market values or company circumstances will not require the Fund to dispose of a holding.

PRINCIPAL INVESTMENT RISKS

Most of the Fund’s performance depends on what happens in the stock market, the Portfolio Managers’ evaluation of those developments, and the success of the Portfolio Managers in implementing the Fund’s investment strategies. The market’s behavior can be difficult to predict, particularly in the short term. There can be no guarantee that the Fund will achieve its goal. The Fund may take temporary defensive and cash management positions; to the extent it does, it will not be pursuing its principal investment strategies.

The actual risk exposure taken by the Fund in its investment program will vary over time, depending on various factors including the Portfolio Managers’ evaluation of issuer, political, regulatory, market, or economic developments. There can be no guarantee that the Portfolio Managers will be successful in their attempts to manage the risk exposure of the Fund or will appropriately evaluate or weigh the multiple factors involved in investment decisions, including issuer, market and/or instrument-specific analysis and valuation.

The Fund is a mutual fund, not a bank deposit, and is not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency. The value of your investment may fall, sometimes sharply, and you could lose money by investing in the Fund.

Each of the following risks, which are described in alphabetical order and not in order of any presumed importance, can significantly affect the Fund’s performance. The relative importance of, or potential exposure as a result of, each of these risks will vary based on market and other investment-specific considerations.

Catalyst Risk. Investing in companies in anticipation of a catalyst carries the risk that the catalyst may not happen as anticipated, or the market may react to the catalyst differently than expected. Certain catalysts, such as emergence from, or restructuring as a result of, bankruptcy, carry additional risks, and the securities of such companies may be more likely to lose value than the securities of more stable companies. Securities of issuers undergoing such an event may be more volatile than other securities, may at times be illiquid, and may be difficult to value, and management of such a company may be addressing a situation with which it has little experience.

Foreign Risk. Foreign securities involve risks in addition to those associated with comparable U.S. securities. Additional risks include exposure to less developed or less efficient trading markets; social, political, diplomatic, or economic instability; trade barriers and other protectionist trade policies (including those of the U.S.); imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals; significant government involvement in an economy and/or market structure; fluctuations in foreign currencies or currency redenomination; potential for default on sovereign debt; nationalization or expropriation of assets; settlement, custodial or other operational risks; higher transaction costs; confiscatory withholding or other taxes; and less stringent auditing and accounting, corporate disclosure, governance, and legal standards. As a result, foreign securities may fluctuate more widely in price, and may also be less liquid, than comparable U.S. securities. World markets, or those in a particular region, may all react in similar fashion to important economic or political developments. In addition, foreign markets may perform differently than the U.S. markets. The effect of economic instability on specific foreign markets or issuers may be difficult to predict or evaluate. Regardless of where a company is organized or its stock is traded, its performance may be affected significantly by events in regions from which it derives its profits or in which it conducts significant operations.

Securities of issuers traded on foreign exchanges may be suspended, either by the issuers themselves, by an exchange, or by governmental authorities. Trading suspensions may be applied from time to time to the securities of individual issuers for reasons specific to that issuer, or may be applied broadly by exchanges or governmental authorities in response to market events. In the event that the Fund holds material positions in such suspended securities or instruments, the Fund’s ability to liquidate its positions or provide liquidity to investors may be compromised and the Fund could incur significant losses.

Foreign Exposure Risk. Securities issued by U.S. entities with substantial foreign operations or holdings, or issued by foreign entities listed on a U.S. exchange, may involve additional risks relating to political, economic, or regulatory conditions in foreign countries, as well as currency exchange rates.

Growth Stock Risk. Because the prices of most growth stocks are based on future expectations, these stocks tend to be more sensitive than value stocks to bad economic news and negative earnings surprises. When these expectations are not met or decrease, the prices of these stocks may decline, sometimes sharply, even if earnings showed an absolute increase. Bad economic news or changing investor perceptions may adversely affect growth stocks across several sectors and industries simultaneously.

Issuer-Specific Risk. An individual security may be more volatile, and may perform differently, than the market as a whole.

Market Volatility Risk. Markets may be volatile and values of individual securities and other investments, including those of a particular type, may decline significantly in response to adverse issuer, political, regulatory, market, economic or other developments that may cause broad changes in market value, public perceptions concerning these developments, and adverse investor sentiment or publicity. Geopolitical and other risks, including environmental and public health risks may add to instability in world economies and markets generally. Changes in value may be temporary or may last for extended periods. If the Fund sells a portfolio position before it reaches its market peak, it may miss out on opportunities for better performance.

Mid-Cap Companies Risk. At times, mid-cap companies may be out of favor with investors. Compared to larger companies, mid-cap companies may depend on a more limited management group, may have a shorter history of operations, less publicly available information, less stable earnings, and limited product lines, markets or financial resources. The securities of mid-cap companies are often more volatile, which at times can be rapid and unpredictable, and less liquid than the securities of larger companies and may be more affected than other types of securities by the underperformance of a sector, during market downturns, or by adverse publicity and investor perceptions.

Recent Market Conditions. Both U.S. and international markets have experienced significant volatility in recent months and years. As a result of such volatility, investment returns may fluctuate significantly. National economies are substantially interconnected, as are global financial markets, which creates the possibility that conditions in one country or region might

adversely impact issuers in a different country or region. However, the interconnectedness of economies and/or markets may be diminishing or changing, which may impact such economies and markets in ways that cannot be foreseen at this time.

Although interest rates were unusually low in recent years in the U.S. and abroad, recently, the Federal Reserve and certain foreign central banks raised interest rates as part of their efforts to address rising inflation. It is difficult to accurately predict the pace at which interest rates might increase or start decreasing, the timing, frequency or magnitude of any such changes in interest rates, or when such changes might stop or reverse course. Additionally, various economic and political factors could cause the Federal Reserve or other foreign central banks to change their approach in the future and such actions may result in an economic slowdown both in the U.S. and abroad. Unexpected changes in interest rates could lead to significant market volatility or reduce liquidity in certain sectors of the market. Deteriorating economic fundamentals may, in turn, increase the risk of default or insolvency of particular issuers, negatively impact market value, cause credit spreads to widen, and reduce bank balance sheets. Any of these could cause an increase in market volatility, or reduce liquidity across various markets or decrease confidence in the markets.

Some countries, including the U.S., have adopted more protectionist trade policies. Slowing global economic growth, the rise in protectionist trade policies, changes to some major international trade agreements, risks associated with the trade agreement between the United Kingdom and the European Union, and the risks associated with trade negotiations between the U.S. and China, could affect the economies of many nations in ways that cannot necessarily be foreseen at the present time. In addition, if the U.S. dollar continues to be strong, it may decrease foreign demand for U.S. assets, which could have a negative impact on certain issuers and/or industries.

Regulators in the U.S. have proposed and adopted a number of changes to regulations involving the markets and issuers, some of which apply to the Fund. The full effect of various newly adopted regulations is not currently known. Additionally, it is not currently known whether any of the proposed regulations will be adopted. However, due to the scope of regulations being proposed and adopted, certain of these changes to regulation could limit the Fund’s ability to pursue its investment strategies or make certain investments, may make it more costly for it to operate, or adversely impact performance.

Tensions, war, or open conflict between nations, such as between Russia and Ukraine, in the Middle East, or in eastern Asia could affect the economies of many nations, including the United States. The duration of ongoing hostilities and any sanctions and related events cannot be predicted. Those events present material uncertainty and risk with respect to markets globally and the performance of the Fund and its investments or operations could be negatively impacted.

High public debt in the U.S. and other countries creates ongoing systemic and market risks and policymaking uncertainty. There is no assurance that the U.S. Congress will act to raise the nation’s debt ceiling; a failure to do so could cause market turmoil and substantial investment risks that cannot now be fully predicted. Unexpected political, regulatory and diplomatic events within the U.S. and abroad may affect investor and consumer confidence and may adversely impact financial markets and the broader economy.

There is widespread concern about the potential effects of global climate change on property and security values. Certain issuers, industries and regions may be adversely affected by the impact of climate change in ways that cannot be foreseen. The impact of legislation, regulation and international accords related to climate change may negatively impact certain issuers and/or industries.

Redemption Risk. The Fund may experience periods of large or frequent redemptions that could cause the Fund to sell assets at inopportune times, which could have a negative impact on the Fund’s overall liquidity, or at a loss or depressed value. Redemption risk is greater to the extent that one or more investors or intermediaries control a large percentage of investments in the Fund and the risk is heightened during periods of declining or illiquid markets. Large redemptions could hurt the Fund’s performance, increase transaction costs, and create adverse tax consequences.

Sector Risk. From time to time, based on market or economic conditions, the Fund may have significant positions in one or more sectors of the market. To the extent the Fund invests more heavily in particular sectors, its performance will be especially sensitive to developments that significantly affect those sectors. Individual sectors or sub-sectors may be more volatile, and may perform differently, than the broader market. The industries that constitute a sector may all react in the same way to economic, political or regulatory events.

Securities Lending Risk. Securities lending involves a possible delay in recovery of the loaned securities or a possible loss of rights in the collateral should the borrower fail financially. The Fund could also lose money if the value of the collateral decreases.

A summary of the Fund’s additional principal investment risks is as follows:

Risk of Increase in Expenses. A decline in the Fund’s average net assets during the current fiscal year due to market volatility or other factors could cause the Fund’s expenses for the current fiscal year to be higher than the expense information presented in “Fees and Expenses.”

Operational and Cybersecurity Risk. The Fund and its service providers, and your ability to transact with the Fund, may be negatively impacted due to operational matters arising from, among other problems, human errors, systems and technology disruptions or failures, or cybersecurity incidents. Cybersecurity incidents may allow an unauthorized party to gain access to fund assets, customer data, or proprietary information, or cause the Fund or its service providers, as well as the securities trading venues and their service providers, to suffer data corruption or lose operational functionality. Cybersecurity incidents can result from deliberate attacks or unintentional events. It is not possible for the Manager or the other Fund service providers to identify all of the cybersecurity or other operational risks that may affect the Fund or to develop processes and controls to completely eliminate or mitigate their occurrence or effects. Most issuers in which the Fund invests are heavily dependent on computers for data storage and operations, and require ready access to the internet to conduct their business. Thus, cybersecurity incidents could also affect issuers of securities in which the Fund invests, leading to significant loss of value.

Risk Management. Risk is an essential part of investing. No risk management program can eliminate the Fund’s exposure to adverse events; at best, it may only reduce the possibility that the Fund will be affected by such events, and especially those risks that are not intrinsic to the Fund’s investment program. The Fund could experience losses if judgments about risk prove to be incorrect.

Valuation Risk. The Fund may not be able to sell an investment at the price at which the Fund has valued the investment. Such differences could be significant, particularly for illiquid securities and securities that trade in relatively thin markets and/or markets that experience extreme volatility. If market or other conditions make it difficult to value an investment, the Fund may be required to value such investments using more subjective methods, known as fair value methodologies. Using fair value methodologies to price investments may result in a value that is different from an investment’s most recent price and from the prices used by other funds to calculate their NAVs. The Fund uses pricing services to provide values for certain securities and there is no assurance that the Fund will be able to sell an investment at the price established by such pricing services. The Fund’s ability to value its investments in an accurate and timely manner may be impacted by technological issues and/or errors by third party service providers, such as pricing services or accounting agents.

PERFORMANCE

The following bar chart and table provide an indication of the risks of investing in the Fund. The bar chart shows how the Fund’s performance has varied from year to year. The table below the bar chart shows what the returns would equal if you averaged out actual performance over various lengths of time and compares the returns with the returns of one or more broad-based market indices. The indices, which are described in “Descriptions of Indices” in the prospectus, have characteristics relevant to the Fund’s investment strategy. The performance information does not reflect variable contract or qualified plan fees and expenses. If such fees and expenses were reflected, returns would be less than those shown. Please refer to the prospectus for your variable contract or your qualified plan documentation for information on their separate fees and expenses.

Returns would have been lower if the Manager had not reimbursed certain expenses and/or waived a portion of the investment management fees during certain of the periods shown.

Past performance is not a prediction of future results. Visit www.nb.com or call 800-877-9700 for updated performance information.

year-by-year % Returns as of 12/31 each year

average annual total % returns as of 12/31/23

INVESTMENT MANAGER

Neuberger Berman Investment Advisers LLC (“Manager”) is the Fund’s investment manager.

PORTFOLIO MANAGERS

The Fund is co-managed by Portfolio Managers Chad Bruso (Managing Director of the Manager), Trevor Moreno (Managing Director of the Manager) and Associate Portfolio Manager Jennifer Blachford (Senior Vice President of the Manager). Messrs. Bruso and Moreno joined as Associate Portfolio Managers in January 2020 and became co-Portfolio Managers in December 2021. Ms. Blachford has managed the Fund since December 2021.

Buying and Selling Shares

The Fund is designed as a funding vehicle for certain variable contracts and qualified plans. Because shares of the Fund are held by the insurance companies or qualified plans involved, you will need to follow the instructions provided by your insurance company or qualified plan administrator for matters involving allocations to the Fund.

When shares of the Fund are bought and sold, the share price is the Fund’s net asset value per share. When shares are bought or sold, the share price will be the next share price calculated after the order has been received in proper form. Shares of the Fund may be purchased or redeemed (sold) on any day the New York Stock Exchange is open.

Tax Information

Distributions made by the Fund to an insurance company separate account or a qualified plan, and exchanges and redemptions of Fund shares made by a separate account or qualified plan, ordinarily do not cause the contract holder or plan participant to recognize income or gain for federal income tax purposes. Please see your variable contract prospectus or the governing documents of your qualified plan for information regarding the federal income tax treatment of the distributions to the applicable separate account or qualified plan and the holders of the contracts or plan participants, respectively.

Payments to Financial Intermediaries

Neuberger Berman BD LLC and/or its affiliates may pay insurance companies or their affiliates, qualified plan administrators, broker-dealers or other financial intermediaries, for services to current and prospective variable contract owners and qualified plan participants who choose the Fund as an investment option. These payments may create a conflict of interest by influencing the financial intermediary and its employees to recommend the Fund over another investment or make the Fund available to their current or prospective variable contract owners and qualified plan participants. Ask your financial intermediary or visit its website for more information.

The “Neuberger Berman” name and logo and “Neuberger Berman Investment Advisers LLC” are registered service marks of Neuberger Berman Group LLC. The individual Fund name in this prospectus is either a service mark or a registered service mark of Neuberger Berman Investment Advisers LLC. ©2024 Neuberger Berman BD LLC, distributor. All rights reserved.

SEC File Number: 811-4255

K0049 05/24