Marshall Wace North America L.P. reported July 21 Calls on XBI US at 135, American (XBI) in 1 quarterly 13F filing .
This page tracks quarterly shares, estimated market value, portfolio weight, filing dates, and disclosure-aligned stock prices directly from SEC EDGAR 13F filings. Older history is available after unlock; the visible window still shows the most recent pattern.
This page is designed to answer the real investor question behind a 13F filing: how meaningful was Marshall Wace North America L.P.'s position in July 21 Calls on XBI US at 135, American, 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.
See the most recent quarter where the fund disclosed this position.
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.
As of 2026 Q2 β sorted by position size
These are the practical questions this page is built to answer before you even open the full history table.
Marshall Wace North America L.P. reported XBI across 0 quarterly 13F filings.
This page shows the quarter-by-quarter portfolio weight history for XBI in Marshall Wace North America L.P..
The most recent filing on this page is 2021 Q2, when Marshall Wace North America L.P. reported 1,000,000 shares, equal to 0.62% of portfolio, with an estimated market value of $135.4M.
The chart compares Marshall Wace North America L.P.'s quarterly XBI 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.