MASON STREET ADVISORS, LLC
Long book
$1.02B
Q1 2026
Positions
15
Top-10 weight
91%
concentration
Last quarter
+8.4%
SPY +14.8%
Turnover
24%
of book per quarter
Strategy in plain words
auto-generated from filingsMASON STREET ADVISORS, LLC is a wealth-management firm allocating client money, running a $1.02B US long book across 15 positions.
The portfolio is extremely concentrated — the top 10 positions are almost the whole book. Turnover is modest: positions are typically held for years. Current anchor positions: ISHARES CORE U.S. AGGREGATE, ISHARES CORE S&P 500 ETF, SS SPDR PF LNG TRM TSY E-USD, SS SPDR P S&P 400 MIDCAP ETF, ISHARES CORE MSCI EAFE ETF.
Over the last 9 quarters its long book ran on average 1.5pp per quarter behind the S&P 500, beating the index in 3 of 9 quarters. Its holdings are mechanical (indexing / client flows), so position changes carry no stock-picking signal.
Implied long-book return vs S&P 500
methodology: positions priced quarterly, no shorts/options Fund long book S&P 500
Q1 2024
+2.1%
Q2 2024
+7.1%
Q3 2024
-3.0%
Q4 2024
+0.5%
Q1 2025
+4.3%
Q2 2025
+4.4%
Q3 2025
+1.9%
Q4 2025
+0.8%
Q1 2026
+8.4%
Sector allocation
No sector data
Long book by quarter
What does MASON STREET own?
Q1 2026 13F| Company | Sector | Shares | Value | % of book | Change |
|---|
13F filing history
| Period | Form | Filed | Entries | Reported value | Flags | Source |
|---|---|---|---|---|---|---|
| Q1 2026 | 13F-HR | May 7, 2026 | 15 | $1.02B | canonical | SEC ↗ |
| Q4 2025 | 13F-HR | Feb 4, 2026 | 15 | $1.02B | canonical | SEC ↗ |
| Q3 2025 | 13F-HR | Oct 31, 2025 | 15 | $964.8M | canonical | SEC ↗ |
| Q2 2025 | 13F-HR | Aug 8, 2025 | 15 | $854.5M | canonical | SEC ↗ |
| Q1 2025 | 13F-HR | May 14, 2025 | 13 | $786.1M | canonical | SEC ↗ |
| Q4 2024 | 13F-HR | Feb 10, 2025 | 12 | $772.6M | canonical | SEC ↗ |
| Q3 2024 | 13F-HR | Nov 12, 2024 | 12 | $823.5M | canonical | SEC ↗ |
| Q2 2024 | 13F-HR | Aug 15, 2024 | 12 | $743.0M | canonical | SEC ↗ |
| Q1 2024 | 13F-HR | May 15, 2024 | 8 | $594.2M | canonical | SEC ↗ |