Prime Money Market Fund: Corporate Paper and 2023 Reforms

Key Takeaways

• Prime money market funds pick up 5–25 basis points over government funds by adding high-quality corporate commercial paper and bank CDs to the portfolio.
• Institutional prime funds carry floating NAV and face a mandatory liquidity fee when daily net redemptions exceed 5% of net assets under the 2023 SEC rules.
• Investors confuse a prime money market fund with a bank deposit; only the bank's money market deposit account is FDIC-insured.
• The 15–25bp yield pickup over government funds disappears and can reverse during stress events, as seen in both 2008 and the March 2020 dash for cash.

What It Is

A prime money market fund is a Rule 2a-7 mutual fund that invests primarily in high-quality, short-duration credit instruments issued by corporations, banks, and non-government entities, with some allocation to Treasuries and repurchase agreements. Common holdings include commercial paper, large negotiable CDs, asset-backed commercial paper, and short-term notes from major financial institutions.

Prime funds are split into two regulatory buckets:

• Retail prime funds. Restricted to natural-person investors. May target a stable 1.00 USD share price.
• Institutional prime funds. Available to entities such as corporations and pension plans. Required to use a floating NAV since the 2016 reforms, with prices stated to four decimal places.

The Intuition

Government money market funds invest only in Treasuries and government-backed repos, which carry the lowest credit risk and usually the lowest yield. Prime funds add unsecured short-term corporate credit, picking up extra yield in exchange for incremental credit and liquidity risk. In normal markets that yield premium runs from 5 to 25 basis points. In stress events the spread can widen sharply or flip negative as the corporate paper market loses bid.

Both the 2008 collapse of the Reserve Primary Fund and the March 2020 dash for cash exposed how quickly prime fund liquidity can dry up. Each episode produced a regulatory response. The 2023 SEC reforms are the latest in that lineage.

How It Works

Rule 2a-7 enforces tight portfolio limits across maturity, credit quality, and diversification. Key constraints include:

• Dollar-weighted average maturity capped at 60 days.
• Average life capped at 120 days.
• High credit quality, with most holdings rated in the top short-term tier.
• Daily and weekly liquidity floors.

The 2023 amendments raised the liquidity floors to 25 percent daily liquid assets and 50 percent weekly liquid assets. They removed the temporary redemption gate authority that had been in effect since 2014, so prime funds can no longer halt redemptions. In its place, the SEC imposed a mandatory liquidity fee on institutional prime and institutional tax-exempt funds. The fee triggers when daily net redemptions exceed 5 percent of net assets unless the fund's costs of providing liquidity are de minimis. Funds may also charge a discretionary liquidity fee of up to 2 percent under board determination.

Retail prime funds remain stable-NAV products. Institutional prime funds remain floating-NAV. Government and Treasury money market funds were not subject to the new mandatory fee framework but were subject to the higher liquidity minimums and adjustments for negative interest rate scenarios.

Worked Example

A treasurer at a midsize company holds 50 million USD in an institutional prime fund yielding 5.20 percent. A government fund yields 5.05 percent. The pickup is 15 basis points, or 75,000 USD per year on the position.

A few months later, market stress widens credit spreads, and the institutional prime fund sees outflows of 8 percent of NAV in a single day. Because the daily net redemption exceeds the 5 percent threshold and liquidity costs are non-trivial, the fund's board determines that a mandatory liquidity fee applies. The fee is set at 1.00 percent of redeemed shares for that day's transactions.

A redemption of 10 million USD that day produces a fee of 100,000 USD, which is paid to the fund and benefits remaining shareholders. Subsequent days return to normal pricing once redemptions fall back below 5 percent of NAV.

A retail prime investor in the same scenario does not face the mandatory fee, because the rule applies only to institutional prime and institutional tax-exempt funds.

Common Mistakes

• Treating retail and institutional prime as the same product. They are governed by different rules. Institutional prime has a floating NAV and a mandatory liquidity fee. Retail prime does not.
• Assuming a stable NAV cannot break. "Breaking the buck" did happen in 2008 with the Reserve Primary Fund. The risk has been reduced by reform but is not zero.
• Ignoring the credit pickup-versus-risk trade. A 15 to 25 basis point pickup over a government fund is real income, but it comes with exposure to commercial paper that can lose liquidity in a crunch.
• Forgetting the post-2023 liquidity fee math. Large institutional cash holders need to model the possible liquidity fee into worst-case redemption costs.
• Conflating prime funds with bank deposits. A money market deposit account at a bank is FDIC-insured. A prime money market fund is a mutual fund and is not.

Frequently Asked Questions

Q: What is a prime money market fund in simple terms? A prime money market fund is a Rule 2a-7 mutual fund that holds short-term corporate debt, commercial paper, bank certificates of deposit, and similar instruments, alongside government securities. It yields slightly more than a government fund by taking on incremental credit risk.

Q: How does a prime money market fund affect investment decisions? It is the standard default for cash held in corporate treasury accounts and high-yield brokerage sweep accounts. The yield premium over government funds is real but modest in calm markets, and it disappears or reverses during credit stress, making the timing of large redemptions critical.

Q: What is a real-world example of the 2023 liquidity fee in action? A corporate treasurer holds $50M in an institutional prime fund. On a stressed day with 8% net outflows and non-trivial liquidity costs, the fund charges a 1% liquidity fee. A $10M redemption that day costs $100,000 in fees that are paid to remaining shareholders, not to the fund manager.

Q: How can investors manage the risks of prime money market funds? Understand whether your account uses a retail or institutional prime class, as only institutional funds face the mandatory liquidity fee. Model worst-case redemption costs if you are a large institutional holder, and for very short-term cash that must be available on demand, consider government funds that carry no mandatory fee.

Q: How is a prime money market fund different from a government money market fund? A government fund invests almost entirely in Treasuries and government-backed repos with essentially no credit risk. A prime fund adds corporate commercial paper and bank CDs for extra yield. In 2008 and 2020, the credit and liquidity differences became acute: government funds held their value while prime funds saw stress.

Sources

1. Securities and Exchange Commission. "Money Market Fund Reforms (Final Rule S7-22-21)." July 2023. https://www.sec.gov/rules-regulations/2023/07/s7-22-21
2. Securities and Exchange Commission. "SEC Adopts Money Market Fund Reforms." Press Release, July 2023. https://www.sec.gov/news/press-release/2023-129
3. Federal Reserve Board. "Money Market Mutual Funds and Stable Funding." Finance and Economics Discussion Series. https://www.federalreserve.gov/econres/feds/files/2014/2014102pap.pdf
4. FINRA. "Money Market Funds." https://www.finra.org/investors/investing/investment-products/money-market-funds

Disclaimer

This article is educational content only and is not financial advice. Nothing here is a recommendation to buy, sell, or hold any security. Consult a licensed advisor before making investment decisions.