By Alex Morgan, March 10, 2026

Sesami

The Birth of Money Market Funds

Money market funds (MMFs) emerged in the United States during the early 1970s, primarily as a response to the challenges individuals and businesses faced amid rising inflation and interest rates. At that time, Regulation Q, introduced in 1933, imposed restrictions on the interest rates that banks could offer on deposits, severely limiting their capacity to attract savings.

In 1971, two visionary entrepreneurs, Bruce Bent and Henry B. R. Brown, took the initiative to address this issue through an innovative vehicle that pooled capital from various savers and used it to invest in short-term debt instruments. The aim was straightforward yet revolutionary: provide a steady return on cash holdings while ensuring the preservation of capital. Their creation, known as the ‘Reserve Fund’, was designed to operate in direct competition with bank deposits, aiming to maintain a stable value per share of $1 while offering daily liquidity and returns closely aligned with the risk-free rate.

Initially, the Reserve Fund launched with only a few hundred thousand dollars and managed to gather $1 million in assets by the beginning of 1973. However, an article published in the New York Times in January 1973 significantly boosted its visibility and investor interest, propelling its assets to approximately $100 million by the year’s end. By the early 1980s, the Reserve Fund had exploded in popularity, managing billions of dollars in assets—a remarkable achievement for a relatively new financial product.

The Rise of Money Market Funds

Motivated by the success of the Reserve Fund, numerous fund managers sought to replicate this model. This led to the introduction of competing products, such as the Fidelity Daily Income Trust (FDIT), which made a significant mark in mid-1974 by offering check-writing privileges. This feature allowed investors to write checks directly from their funds, similar to how bank accounts functioned. Today, Fidelity Investments has grown to become the largest MMF manager in the U.S., boasting over $1.5 trillion in MMF assets and a market share of around 20%.

The proliferation of MMFs in the U.S. during the late 20th century was noteworthy; from a handful of funds in the early 1970s, the number exceeded 600 by 1990. Throughout the decade, MMFs became an essential tool for cash management, appealing to individual savers as well as institutional treasurers, either as a complement to or a substitute for traditional bank deposits.

Though the regulations limiting deposit rates were gradually eased in the 1980s—culminating in the repeal of these regulations in 1986—banks were often hesitant to raise their interest rates, thereby preserving the attractiveness of MMFs. By the 1990s and into the early 2000s, MMFs like the Reserve Fund played a vital role in short-term credit markets, providing financing to banks, corporations, and government entities. However, it is important to note that many of these funds were still primarily invested in private debt securities, which would later lead to significant complications.

‘Breaking the Buck’: The Reserve Fund’s Downfall

The Reserve Fund enjoyed continuous growth, maintaining its $1 net asset value (NAV) for decades and surpassing $60 billion in assets by 2008. Yet, everything changed dramatically on September 15, 2008, with the bankruptcy filing of Lehman Brothers. The Reserve Fund’s holdings included $785 million of Lehman’s short-term debt, which instantaneously lost its value, triggering a drop in the fund’s NAV below $1, thereby causing capital losses for its investors. This event marked a historic first for the U.S. retail-focused MMF sector, as it was the first time a significant fund had broken the buck.

As the NAV fell below the prudently maintained threshold, alarm swept through the Reserve Fund’s investor base. The subsequent day saw $15 billion in redemption requests flood in. In response, the fund’s managers made the difficult decision to freeze redemptions for institutional investors while continuing to process withdrawals for retail investors. This loss of confidence quickly escalated beyond the Reserve Fund, extending to other MMFs with exposure to private debt securities, culminating in over $400 billion in redemption requests within days.

On September 19, the U.S. Treasury launched a temporary guarantee program aimed at stabilizing the MMF market and reassuring investors about the safety of their capital. This program allowed participating funds to guarantee their shareholders’ accounts, ensuring that NAVs would not fall below $1. Fortunately, this initiative successfully stemmed the tide of investor panic and gradually restored confidence in MMFs.

Nevertheless, the Reserve Fund ultimately wound down its operations—allowing its assets to mature or being sold off gradually to culminate in distributions to remaining investors. Remarkably, the losses were limited to around 1%, principally reflecting exposure to Lehman Brothers’ debt.

Lessons Learned: From ‘Prime MMFs’ to ‘Government MMFs’

The fallout from the Reserve Fund’s collapse led to substantial shifts within the U.S. MMF space. Following this crisis, the SEC implemented a rule in 2014, fully effective by 2016, requiring so-called ‘Prime MMFs’ to adopt a floating NAV, which meant share prices could no longer be fixed at $1. In light of these changes and increased investor apprehensions regarding credit risk, fund managers pivoted their portfolios towards government securities, particularly Treasury bills.

Prior to 2008, Prime MMFs accounted for around 80% of the market. However, by 2010, Government MMFs had overtaken with more than 50% of total assets. Presently, they command over 80% of total MMF assets in the U.S. market. The underlying appeal is clear: Government MMFs have never broken the buck, and barring a default on U.S. government debt, it is improbable that any ever will. Thus, the unfortunate events surrounding the Reserve Fund ultimately contributed to the fortification and evolution of the MMF industry.

Contrastingly, the European MMF landscape has not mirrored this transition. Despite the cautionary tale presented by the Reserve Fund’s abrupt decline, many European MMFs continue to invest predominantly in short-term debt issued by private entities. Nonetheless, exceptions exist, such as the Spiko Euro money market fund, which adheres to a more conservative strategy by maintaining a 100% allocation to Treasury bills.

Understanding Fidelity Money Market Rates

During all periods of evolution within money market funds, investors have consistently sought better yields on their cash holdings. One notable approach taken by various funds involves adjusting fidelity money market rates to offer competitive returns while maintaining safety. As the financial landscape continues to evolve, funds adapting their strategies to maximize these rates will draw increased investor interest, implying a shift towards more robust and promising offerings.

Conclusion

The evolutionary journey of money market funds tells a compelling story of innovation in finance—one that began in response to regulatory constraints and market needs. While the industry has shown remarkable resilience, it has not been without its challenges. Investors must remain vigilant, understanding the dynamic nature of these funds and the implications surrounding shifts in market strategies and allocations. With the evolving landscape of money market products, resources such as the Sesami website serve as invaluable tools for gaining deeper insights and understanding the diverse offerings within the cash management arena.

Disclaimer: The information presented in this article does not constitute financial advice. Always consult with a qualified financial advisor before making investment decisions.