MASON STREET ADVISORS, LLC

Insurance Manager

MASON STREET ADVISORS, LLC is an Insurance Manager based in Milwaukee, WI led by Bonnie Lynn Tomczak, reporting $35.0B in AUM as of Q3 2025 with 100% ETF concentration, 92% concentrated in top 10 holdings, and 32% allocation to AGG.

ChairmanBonnie Lynn Tomczak

Portfolio Value: $964.8M
Positions: 15
Top Holding: AGG at 31.58%
Last Reported: Q3 2025

Address720 East Wisconsin Avenue, Milwaukee, WI, 53202-4797, United States

Top Holdings

Largest long holdings in MASON STREET ADVISORS, LLC's portfolio (91.5% of total portfolio)

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Holding	Sector	Position	Weight	Traded	Ownership	Owned Since
1 iShares Core U.S. Aggregate Bond AGG	ETF ETF	$304.7M	31.58%	+$24.8M Bought	— 3.0M shares	Q1 2017 Held for 8y 8m
2 iShares Core S&P 500 ETF IVV	ETF ETF	$140.3M	14.55%	-$40.3M Sold	— 209.7K shares	Q4 2016 Held for 8y 11m
3 SPDR Portfolio Long Term Treasury SPTL	ETF ETF	$106.8M	11.07%	+$2.4M Bought	— 4.0M shares	Q2 2024 Held for 1y 5m
4 SPDR Portfolio S&P 400 Mid Cap ETF SPMD	ETF ETF	$77.9M	8.07%	+$24.9M Bought	— 1.4M shares	Q2 2024 Held for 1y 5m
5 iShares Core MSCI EAFE ETF IEFA	ETF ETF	$55.2M	5.72%	+$5.2M Bought	— 631.8K shares	Q1 2022 Held for 3y 8m
6 SPDR Portfolio S&P 600 Small Cap ETF SPSM	ETF ETF	$53.9M	5.59%	+$3.5M Bought	— 1.2M shares	Q1 2024 Held for 1y 8m
7 iShares MSCI USA Value Factor VLUE	ETF ETF	$40.0M	4.15%	+$40.0M New	— 320.0K shares	Q3 2025 Held for 2 months
8 SPDR Dow Jones REIT RWR	ETF ETF	$35.7M	3.70%	+$3.5M Bought	— 355.8K shares	Q2 2024 Held for 1y 5m
9 Schwab U.S. REIT SCHH	ETF ETF	$35.1M	3.64%	+$3.0M Bought	— 1.6M shares	Q2 2024 Held for 1y 5m
10 IQLT iShares MSCI Intl Quality Factor IQLT	ETF ETF	$33.2M	3.44%	+$2.6M Bought	— 751.4K shares	Q2 2025 Held for 5 months

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Changes

Portfolio activity, position movements, and quarter-over-quarter changes in MASON STREET ADVISORS, LLC's latest filing

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Market Value

$964.8M

Prior: $854.5M

Q/Q Change

+12.9%

+$110.3M

Net Flows % of MV

+8.15%

Turnover Ratio

9.38%

New Purchases

1 stocks

$40.0M

Added To

12 stocks

+$89.7M

Sold Out Of

2 stocks

$10.8M

Reduced Holdings

1 stocks

-$40.3M

Increased Positions

Position	Shares Δ	Change
1 iShares MSCI USA Value Factor VLUE	New	0 → 320.0K +$40.0M
2 JPMorgan Ultra-Short Income JPST	+116.28%	216.7K → 468.6K +$12.8M
3 SPDR Portfolio S&P 400 Mid Cap ETF SPMD	+46.85%	927.6K → 1.4M +$24.9M
4 abrdn Bloomberg All Commodity Strategy K-1 Free ETF BCI	+31.07%	304.9K → 399.6K +$2.0M
5 Invesco S&P 500 Equal Weight ETF RSP	+14.66%	133.1K → 152.6K +$3.7M

Decreased Positions

Position	Shares Δ	Change
1 iShares Core S&P Mid-Cap ETF IJH	Sold	98.6K → 0 −$6.1M
2 iShares Core S&P Small-Cap ETF IJR	Sold	42.6K → 0 −$4.7M
3 iShares Core S&P 500 ETF IVV	-22.33%	270.0K → 209.7K −$40.3M