US ETF · ETF

ISHARES TR MBB

The iShares MBS ETF (MBB) is an exchange-traded fund that mostly invests in investment grade fixed income. The fund tracks a market-weighted index of investment-grade mortgage pass-through securities. The index includes fixed and floating rate securities issued by GNMA, FNMA and FHLMC. MBB was launched on Mar 13, 2007 and is issued by BlackRock.

Exchange Traded Fund

Company profile

Business mix

  • The fund tracks a market-weighted index of investment-grade mortgage pass-through securities.
  • The index includes fixed and floating rate securities issued by GNMA, FNMA and FHLMC.
  • The fund gives investors fixed income / government mortgage-backed bond exposure through a listed ETF structure.
  • It tracks the Bloomberg US Aggregate Securitized - MBS index and is issued by BlackRock.
  • Portfolio breadth and cost are visible in 11169 holdings and a 0.04% expense ratio.

Current key questions

  • Does the fund's index exposure, fees, liquidity, and tracking quality fit the role investors expect it to play?
  • How concentrated is the portfolio by issuer, sector, country, factor, or duration risk?
  • Can flows, spreads, and market structure affect trading costs during volatile periods?
Holders 1 Current sample portfolio
Public mentions 0 Videos / interviews / letters

Current firm holders

Firm Weight Value Filing period
Bridgewater Associates Ray Dalio 0.6% $129.1M 2026-03-31

Recent trading changes over the last 4 quarters

Net buyers 0 Last 4 13F filing periods
Net reducers 1 Last 4 13F filing periods
Unchanged holders 0 Share count unchanged
Increase amount $0 Estimated from net added shares
Reduction amount $8.3M Estimated from net reduced shares
Net share change / base shares -6.1% -87,600 / 1,447,600
Bridgewater Associates Ray Dalio 4 filing periods
13F 2025-06-30 Filed 2025-08-13
Minor increase Shares 0.9% 13F value change +$1.3M
13F 2025-09-30 Filed 2025-11-13
Minor reduction Shares -7.2% 13F value change -$8.2M
13F 2025-12-31 Filed 2026-02-13
Minor increase Shares 1.5% 13F value change +$2.0M
13F 2026-03-31 Filed 2026-05-15
Minor reduction Shares -1.1% 13F value change -$1.8M
Settlement As of 13F 2026-03-31 · Filed 2026-05-15
Base shares 1,447,600 Last 4 periods -87,600 (-6.1%) Total shares 1,360,000 Value $129.1M

Recent mentions

No public mentions.