iShares MBS ETF
937 hedge funds and large institutions have $32B invested in iShares MBS ETF in 2025 Q1 according to their latest regulatory filings, with 109 funds opening new positions, 326 increasing their positions, 407 reducing their positions, and 74 closing their positions.
1,218% more call options, than puts
Call options by funds: $57.7M | Put options by funds: $4.38M
47% more first-time investments, than exits
New positions opened: 109 | Existing positions closed: 74
11% more funds holding in top 10
Funds holding in top 10: 61 → 68 (+7)
1% more funds holding
Funds holding: 927 → 937 (+10)
5.14% less ownership
Funds ownership: 91.84% → 86.7% (-5.1%)
20% less repeat investments, than reductions
Existing positions increased: 326 | Existing positions reduced: 407
42% less capital inflows, than outflows
Capital inflows: $1.78B | Capital outflows: $3.06B
Top Buyers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
RenaissanceRe Holdings
Pembroke,
Bermuda
|
+$264M |
| 2 |
LPL Financial
San Diego,
California
|
+$222M |
| 3 |
Fisher Asset Management
Camas,
Washington
|
+$124M |
| 4 |
UBS AM
Chicago,
Illinois
|
+$97.4M |
| 5 |
Jane Street
New York
|
+$83.9M |
Top Sellers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
Bank of America
Charlotte,
North Carolina
|
-$1.24B |
| 2 |
Essential Planning
Portsmouth,
New Hampshire
|
-$301M |
| 3 |
Envestnet Asset Management
Chicago,
Illinois
|
-$199M |
| 4 |
Envestnet Portfolio Solutions
Chicago,
Illinois
|
-$111M |
| 5 |
RWA Wealth Partners
Newton,
Massachusetts
|
-$91.4M |
MBB Hedge Fund Activity: Q1 2025 in Review
937 of the 7,481 institutional investors tracked by Wall St. Rank reported a position in iShares MBS ETF (MBB) for Q1 2025, worth a combined $32B — down 2% from $32.6B a quarter earlier.
Buyers outnumbered sellers: 109 funds opened new MBB positions and 74 closed out — a net gain of 35 holders — while 326 added to existing stakes and 407 trimmed.
The largest buyer was RenaissanceRe Holdings, opening a new position worth an estimated $264M. The largest seller was Bank of America, cutting an estimated $1.24B.
- 937 institutional investors held iShares MBS ETF (MBB) as of Q1 2025, up from 927 in Q4 2024.
- Funds reported $32B of iShares MBS ETF stock for Q1 2025, down 2% quarter-over-quarter.
- 109 funds opened new iShares MBS ETF positions in Q1 2025 and 74 closed out, a net change of +35 holders.
- The largest iShares MBS ETF buyer in Q1 2025 was RenaissanceRe Holdings, an estimated $264M added.
- The largest iShares MBS ETF seller in Q1 2025 was Bank of America, an estimated $1.24B sold.
Based on aggregated 13F filings for Q1 2025.