Understanding Money Market Funds: TSTXX and MULSX
Last updated March 21, 2026
What are Money Market Funds?
Money market funds are a type of mutual fund that invests in short-term, high-quality debt securities. They're designed to offer investors a safe place to invest easily accessible cash while earning competitive yields. When you enable Treasury on your Slash account, your idle cash is automatically invested in money market funds to earn yield.
The Two Funds Available Through Slash Treasury
- TSTXX - Treasury Obligations Portfolio (Dreyfus)
- Fund Type: Government money market fund
- Primary Investments: U.S. Treasury securities, repurchase agreements backed by U.S. Treasury securities
- Risk Profile: Ultra-low risk
- Best For: Customers seeking maximum safety with U.S. government backing
TSTXX invests at least 99.5% of its total assets in cash, U.S. Treasury securities, and repurchase agreements collateralized by U.S. Treasury securities. This fund is designed to maintain a stable $1.00 share price.
- MULSX - MFS Ultra Short Duration Fund
- Fund Type: Ultra-short bond fund
- Primary Investments: Investment-grade short-term debt securities including corporate bonds, commercial paper, and government securities
- Risk Profile: Low risk (slightly higher than government-only funds)
- Best For: Customers comfortable with marginally higher risk for potentially higher yields
MULSX invests in a diversified mix of investment-grade short-term debt, typically with an average portfolio duration of less than one year. This diversification may provide enhanced yield potential.
Key Differences Between the Funds
| Feature | TSTXX | MULSX |
| Investment Focus | Government securities only | Diversified short-term debt |
| Risk level | Lowest | Low |
| Yield potential | Competitive | Potentially higher |
| Government backing | Yes (U.S. Treasury) | No (Investment-grade corporate) |
Important Things to Know
- No FDIC Insurance: Unlike bank deposits, money market funds are securities. They are NOT insured by the FDIC.
- SIPC Protection: Your Treasury investments are protected by SIPC (Securities Investor Protection Corporation) for up to $500,000 in the event of brokerage failure.
- Yields are Net of Fees: The yield you see displayed in Slash is net of management fees—what you see is what you earn.
- No Minimum Balance: There's no minimum balance requirement to start earning yield on your Treasury account.
- Liquidity: Funds are typically available within 1-2 business days when you transfer back to your checking account.
How Slash Allocates Your Funds
When you deposit money into Treasury, Slash automatically allocates your funds to these money market investments based on current market conditions and availability. The goal is to maximize your yield while maintaining high liquidity and capital preservation.
Yield Display
The "Net 7-day yield" shown in your account reflects the actual yield you'll earn after all fund expenses are deducted. This number is calculated based on the fund's performance over the trailing seven days, annualized.
Questions?
Contact our support team at support@slash.com if you have questions about how Treasury works or the money market funds we use.
Can’t find what you’re looking for?
Our support team is available 24/7 to help you with any questions.