# Index 400 Stock Portfolio

Index 400 Stock Portfolio is a registered fund series of NORTHWESTERN MUTUAL SERIES FUND INC (series S000000054). Net assets $1.5B as of 2026-03-31. Index fund.

## Profile

- Series ID: S000000054
- Registrant: NORTHWESTERN MUTUAL SERIES FUND INC
- LEI: 11EBFDHR7ZLPMGNIIF96
- Net assets: $1.5B
- Total assets: $1.5B
- 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 |
| --- | --- | --- | --- |
| TechnipFMC PLC | — | $13.0M | 86.43% |
| [Casey's General Stores Inc](https://search.stillhousedata.com/security/147528103) | — | $12.5M | 83.40% |
| [United Therapeutics Corp](https://search.stillhousedata.com/security/91307C102) | — | $11.9M | 78.92% |
| [Curtiss-Wright Corp](https://search.stillhousedata.com/security/231561101) | — | $11.7M | 77.62% |
| Flex Ltd | — | $11.2M | 74.40% |
| [XPO Inc](https://search.stillhousedata.com/security/983793100) | — | $10.6M | 70.45% |
| [Woodward Inc](https://search.stillhousedata.com/security/980745103) | — | $9.9M | 65.96% |
| [Royal Gold Inc](https://search.stillhousedata.com/security/780287108) | — | $9.6M | 63.74% |
| [US Foods Holding Corp](https://search.stillhousedata.com/security/912008109) | — | $9.5M | 62.86% |
| [Burlington Stores Inc](https://search.stillhousedata.com/security/122017106) | — | $9.4M | 62.54% |
| [ATI Inc](https://search.stillhousedata.com/security/01741R102) | — | $9.2M | 61.09% |
| [MasTec Inc](https://search.stillhousedata.com/security/576323109) | — | $9.2M | 61.00% |
| [Carpenter Technology Corp](https://search.stillhousedata.com/security/144285103) | — | $9.1M | 60.69% |
| nVent Electric PLC | — | $8.9M | 59.00% |
| [Twilio Inc](https://search.stillhousedata.com/security/90138F102) | — | $8.9M | 58.97% |

## Net asset history

| Report date | Net assets |
| --- | --- |
| 2026-03-31 | $1.5B |
| 2025-12-31 | $1.5B |
| 2025-09-30 | $1.5B |
| 2025-06-30 | $1.4B |
| 2025-03-31 | $1.3B |
| 2024-12-31 | $1.4B |
| 2024-09-30 | $1.4B |
| 2024-06-30 | $1.3B |

## 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/S000000054.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.