MBB vs MTGP

MBBAiShares MBS ETF

MTGPCWisdomTree Mortgage Plus Bond Fund

In short

MBB Launched in 2007, MBB is the plain-vanilla way to own U.S. agency mortgage bonds: one of the biggest and busiest funds in a small niche, tracking the Bloomberg U.S. MBS Index for four basis points.

MTGP Most mortgage ETFs are index machines bolted to agency pass-throughs. MTGP is the active counterpunch: a manager picking across mortgage and other securitized debt, hunting income and price gains, and paying out monthly.

Stated mandate

MBB The fund seeks to track an index composed of U.S. agency mortgage-backed securities.

MTGP The fund is actively managed and seeks income and capital appreciation by investing in mortgage-related debt and other securitized debt.

Why people hold it

• MBB Four basis points to rent the entire agency mortgage market, against a category median near 0.35%. In low-coupon bond land, that gap compounds quietly.
• Scale is the real feature: one of the largest and most actively traded funds in the mortgage-bond category, which generally shows up as tighter spreads.
• Pays monthly, and the mandate stays narrow: an index of U.S. agency mortgage-backed securities, nothing exotic bolted on.
• Among the stronger builds in a thin peer group of mortgage-bond ETFs, on the combination of cost, trading friction and issuer staying power.

• MTGP Actively managed, not index-bound. The mandate reaches beyond plain agency paper into mortgage-related and other securitized debt, so a manager sets the mix instead of a benchmark.wisdomtree.com
• Pays monthly, which suits investors who want mortgage-bond income arriving on a regular cadence rather than quarterly.
• Spreads its bets across a couple hundred securitized positions, so no single pool or deal dominates the book.
• Running since 2019 under WisdomTree, giving the active approach a multi-year track record through a brutal stretch for mortgage bonds.

Worth knowing

• MBB This is one slice of the bond market. Agency mortgage paper only, with no Treasuries or corporates alongside it.
• Mortgage bonds cut both ways with rates: borrowers refinance when yields fall and sit tight when they rise, so the portfolio's duration shifts underneath you.
• On price it's a photo finish: SPMB tracks the same index at the same 0.04%, and VMBS runs a basis point cheaper.

• MTGP Active costs money: 0.45% a year, while index rivals like VMBS (0.03%) and SPMB (0.04%) charge a sliver of that. The manager has to out-earn the gap.
• Thinly traded and modest in size, so spreads can be wider than the giant index MBS funds and large orders may need care.
• On our combined read of cost, tradability and mandate delivery, it lands in the lower half of the mortgage-bond ETF pack.

Full MBB profile⁠

Full MTGP profile⁠