WESTFIELD CAPITAL MANAGEMENT CO LP reported NATERA INC (NTRA) in 6 quarterly 13F filings from 2024 Q4 through 2026 Q1. Peak portfolio weight reached 0.68% in 2025 Q4. The latest visible filing shows NTRA at 0.63% of the fund.
This page tracks quarterly shares, estimated market value, portfolio weight, filing dates, and disclosure-aligned stock prices directly from SEC EDGAR 13F filings.
This page is designed to answer the real investor question behind a 13F filing: how meaningful was WESTFIELD CAPITAL MANAGEMENT CO LP's position in NATERA INC, and how did that conviction change over time? You can read the holding window, peak weight, latest reported size, disclosure timing, and quarter-by-quarter changes without piecing the story together from raw SEC rows.
NTRA was reported at 0.63% of portfolio in the most recent visible filing.
Peak weight helps separate a token disclosure from a real conviction holding the fund genuinely cared about.
Longer holding windows often tell a very different story from short-lived tactical trades or one-quarter experiments.
Knowing that a fund owned a stock is useful. Knowing whether it was a 0.20% placeholder or a true high-conviction position is where the signal actually starts.
These are the practical questions this page is built to answer before you even open the full history table.
WESTFIELD CAPITAL MANAGEMENT CO LP reported NTRA across 6 quarterly 13F filings, from 2024 Q4 through 2026 Q1.
The largest reported portfolio weight for NTRA was 0.68% in 2025 Q4.
The most recent filing on this page is 2026 Q1, when WESTFIELD CAPITAL MANAGEMENT CO LP reported 754,729 shares, equal to 0.63% of portfolio, with an estimated market value of $150.9M.
The chart compares WESTFIELD CAPITAL MANAGEMENT CO LP's quarterly NTRA portfolio weight with the stock's indexed share price, so you can see whether the fund was building, trimming, or holding the position as price moved.
Based on 13F filing dates vs. subsequent NTRA price moves, WESTFIELD CAPITAL MANAGEMENT CO LP correctly timed 1 out of 5 reported position changes (20%). The annualised alpha on NTRA relative to SPY over the holding period was -4.3%.