MCBYX — MassMutual Core Bond Fund
Data updated: 2026-08-27
MCBYX — MassMutual Core Bond Fund. Long Total / Aggregate Bond · $846.76M AUM · 0.53% expense ratio. Holdings, fees, performance and SEC filings.
MCBYX Fund Overview
MCBYX — MassMutual Core Bond Fund is a US mutual fund managed by Massmutual Premier Funds, categorised as Long Total / Aggregate Bond. ABC INVEST provides holdings, performance, costs, cashflows, risk data, prospectus documents and SEC filings, sourced from SEC filings.
- Type: US mutual fund
- Manager: Massmutual Premier Funds
- Category: Long Total / Aggregate Bond
- Assets under management: $846.76M
- 1-year return: 5.1%
- Ticker: MCBYX
- SEC CIK: 0000927972
- SEC series ID: S000003791
- Share class ID: C000010547
MCBYX Holdings
Top 10 holdings of MassMutual Core Bond Fund by percentage of net assets, from the fund's latest SEC N-PORT filing.
| Holding | % of net assets |
|---|---|
| Umbs, Tba | 3.63% |
| Freddie Mac | 2.00% |
| United States Treasury | 1.98% |
| United States Treasury | 1.79% |
| United States Treasury | 1.69% |
| Umbs, Tba | 1.45% |
| State Street Global Advisors | 1.35% |
| EIDP Inc | 1.18% |
| Becton Dickinson & Co | 1.18% |
| United States Treasury | 1.16% |
MCBYX Portfolio Allocation
Asset-class allocation of MassMutual Core Bond Fund by percentage of net assets, from the latest SEC N-PORT filing.
| Asset class | Allocation |
|---|---|
| Fixed Income | 50.7% |
| Securitized | 47.1% |
| Cash & Equivalents | 9.2% |
| Real Estate | 0.2% |
MCBYX Performance
Total returns for MCBYX (as of 2026-09-01), from SEC filings.
| Period | Total return |
|---|---|
| YTD | 1.3% |
| 1 year | 5.1% |
| 3 years (annualised) | 5.9% |
| 5 years (annualised) | 0.5% |
MCBYX Risk Information
Risk metrics for MCBYX, derived from monthly returns in SEC filings.
- 1-year volatility (annualised): 3.0%
MCBYX Costs and Fees
MCBYX costs about $53 per $10,000 invested per year in fund expenses.
- Net expense ratio: 0.53%
- Gross expense ratio: 0.57%
- Portfolio turnover: 149%
- Brokerage commissions: 0.48 bps of average net assets (SEC N-CEN)
MCBYX Cashflows
Over the 12 months to 2026-06, MassMutual Core Bond Fund had net inflows of $58.84M, from monthly SEC N-PORT filings.
| Month | Net flow |
|---|---|
| 2026-06 | −$3.36M |
| 2026-05 | $6.97M |
| 2026-04 | −$3.99M |
| 2026-03 | $25.84M |
| 2026-02 | −$16.54M |
| 2026-01 | $3.40M |
MCBYX Debt Constituents
Largest debt holdings of MassMutual Core Bond Fund by percentage of net assets, from the latest SEC N-PORT filing.
| Debt holding | % of net assets |
|---|---|
| United States Treasury | 1.98% |
| United States Treasury | 1.79% |
| United States Treasury | 1.69% |
| United States Treasury | 1.16% |
| Fidus Re Ltd. | 0.70% |
| United States Treasury | 0.69% |
| Corebridge Financial, Inc. | 0.62% |
| Allianz SE | 0.60% |
| Enstar Finance LLC | 0.60% |
| Antares Holdings | 0.50% |
MCBYX Prospectus and SEC Filings
Official MassMutual Core Bond Fund filings on SEC EDGAR — prospectus, portfolio holdings and annual reports.
- Prospectus (485BPOS) — filed 2026-01-30
- Prospectus (485BPOS) — filed 2025-01-31
- Prospectus supplement (497) — filed 2025-09-23
- Portfolio holdings (N-PORT) — filed 2026-08-27
- Portfolio holdings (N-PORT) — filed 2026-05-27
- Portfolio holdings (N-PORT) — filed 2026-02-26
- Annual census (N-CEN) — filed 2025-12-12
- Annual census (N-CEN) — filed 2024-12-13
Related Funds
Other Long Total / Aggregate Bond funds tracked on ABC INVEST:
Data Sources
ABC INVEST compiles this page from public filings made to the U.S. Securities and Exchange Commission (SEC) through EDGAR: portfolio holdings and monthly cashflows from Form N-PORT, expenses and returns from fund prospectuses (Form 485BPOS) and the SEC DERA Risk/Return Summary data sets, annual data from Form N-CEN, and shareholder reports from Form N-CSR.