MBBA vs VMBS

MBBACiShares Mortgage-Backed Securities Active ETF

VMBSAVanguard Mortgage-Backed Securities ETF

In short

MBBA Active management aimed at the plumbing of the mortgage market: iShares gives a manager room to pick agency MBS instead of mirroring the Bloomberg U.S. MBS Index, and charges less than the typical fund in this corner to do it.

VMBS The plumbing of the U.S. housing market in one ticker: pooled home loans from Ginnie, Fannie and Freddie, tracked by index for 0.03% a year, with income paid monthly.

Stated mandate

MBBA The Fund seeks to maximize total return while generating income and applying prudent investment management.

VMBS The fund seeks moderate and sustainable current income by investing primarily in U.S. agency mortgage-backed pass-through securities issued by GNMA, FNMA, and FHLMC.

Why people hold it

• MBBA Runs at 0.25% a year, under the 0.35% typical of MBS funds in its group. Active mandates usually charge up from the index, not down toward it.
• The mandate: maximize total return while generating income. The Bloomberg U.S. MBS Index is the yardstick, not a leash the manager has to hug bond for bond.
• Spread across roughly 500 US mortgage bonds in a plain 1940 Act open-end fund. No K-1, no derivative wrapper, no offshore structure to decode.
• Fund inception dates to 1998, meaning this mortgage playbook was running long before most of the ETFs it now sits beside existed.

• VMBS 0.03% a year is the cheap end of the mortgage-bond aisle: SPMB and MBB charge 0.04%, JMTG 0.24%, and the typical peer runs far higher.
• Agency pass-throughs from GNMA, FNMA and FHLMC. Credit isn't the main variable here; rates and mortgage behavior are.vanguard.com
• Trading since 2009, a multi-billion-dollar fund holding roughly 300 pools and paying monthly. Boring in the way bond ballast is supposed to be.
• Sits in the top quartile of its mortgage-bond peer group, one of the stronger builds in a crowded, look-alike category.

Worth knowing

• MBBA Cheap for active, still pricier than the index route: MBB, VMBS and SPMB all sit at a few basis points. Here you are paying for a manager's calls.
• Because it is active, there is no tracking record to audit, and only a short window of risk history exists. Less to measure than a long-running tracker.
• Smaller and more lightly traded than the index heavyweights in the MBS category, which is where limit orders earn their keep.

• VMBS Mortgages don't keep a schedule. Homeowners refinance when rates fall, returning cash to reinvest at lower yields; when rates rise, payoffs slow and bonds stretch out.vanguard.com
• The mandate is current income from one slice of the bond market. No Treasuries, no corporates, no equity kicker.
• Share prices move with interest rates, so this behaves like a bond fund, not a cash parking spot.vanguard.com

Full MBBA profile⁠

Full VMBS profile⁠