# Index 600 Stock Portfolio

Index 600 Stock Portfolio is a registered fund series of NORTHWESTERN MUTUAL SERIES FUND INC (series S000018231). Net assets $525.9M as of 2026-03-31. Index fund.

## Profile

- Series ID: S000018231
- Registrant: NORTHWESTERN MUTUAL SERIES FUND INC
- LEI: H4V7XOKHREX82GREV795
- Net assets: $525.9M
- Total assets: $529.9M
- As of: 2026-03-31
- Type: Index

## Advisers

- [Northern Trust Investments, Inc. (Subadvisor)](https://search.stillhousedata.com/firm/105780)
- [Mason Street Advisors, LLC (Advisor)](https://search.stillhousedata.com/firm/114085)

## Top holdings (200 reported)

_Showing 15 of 200 holdings by value._

| Holding | Ticker | Value | % of fund |
| --- | --- | --- | --- |
| [Eastman Chemical Co](https://search.stillhousedata.com/security/277432100) | — | $3.0M | 56.54% |
| [Element Solutions Inc](https://search.stillhousedata.com/security/28618M106) | — | $2.7M | 50.45% |
| [Primoris Services Corp](https://search.stillhousedata.com/security/74164F103) | — | $2.6M | 50.20% |
| [Viavi Solutions Inc](https://search.stillhousedata.com/security/925550105) | — | $2.6M | 50.09% |
| [Argan Inc](https://search.stillhousedata.com/security/04010E109) | — | $2.6M | 49.15% |
| [FormFactor Inc](https://search.stillhousedata.com/security/346375108) | — | $2.6M | 48.91% |
| [LKQ Corp](https://search.stillhousedata.com/security/501889208) | — | $2.6M | 48.80% |
| [Jackson Financial Inc](https://search.stillhousedata.com/security/46817M107) | — | $2.6M | 48.58% |
| [ESCO Technologies Inc](https://search.stillhousedata.com/security/296315104) | — | $2.5M | 47.34% |
| [Match Group Inc](https://search.stillhousedata.com/security/57667L107) | — | $2.5M | 47.05% |
| [Celanese Corp](https://search.stillhousedata.com/security/150870103) | — | $2.5M | 46.85% |
| [Semtech Corp](https://search.stillhousedata.com/security/816850101) | — | $2.4M | 46.29% |
| [Armstrong World Industries Inc](https://search.stillhousedata.com/security/04247X102) | — | $2.4M | 46.24% |
| [Sanmina Corp](https://search.stillhousedata.com/security/801056102) | — | $2.4M | 46.05% |
| [SM Energy Co](https://search.stillhousedata.com/security/78454L100) | — | $2.4M | 45.83% |

## Net asset history

| Report date | Net assets |
| --- | --- |
| 2026-03-31 | $525.9M |
| 2025-12-31 | $514.5M |
| 2025-09-30 | $509.2M |
| 2025-06-30 | $471.8M |
| 2025-03-31 | $438.7M |
| 2024-12-31 | $476.3M |
| 2024-09-30 | $483.2M |
| 2024-06-30 | $438.7M |

## More

- [Registrant: NORTHWESTERN MUTUAL SERIES FUND INC](https://search.stillhousedata.com/registrant/742212)
- [This page as markdown (for LLM agents)](https://search.stillhousedata.com/fund/S000018231.md)
- [Search all SEC filings, advisers and people on Adviser Search](https://search.stillhousedata.com/)

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Source: public SEC filing data via Adviser Search (https://search.stillhousedata.com).
Agents: this data is also queryable via MCP tools and read-only SQL — see https://search.stillhousedata.com/llms.txt.