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Yahoo's insider_purchases field counts RSU grants and option conversions as "purchases"

static 2026-07-31

Claim

mcp__yahoo-finance__get_holder_info(holder_type="insider_purchases") returns a summary block with "Purchases", "Net Shares Purchased" and "% Buy". Those fields do not mean open-market buying. They aggregate every acquisition-side Form 4 code, including:

  • RSU/PSU vesting recorded at $0.00
  • Option exercises at legacy strikes (on RBLX: $3.40, $0.53, $0.06 — pre-IPO grants)

The case that caught it

RBLX, 2026-07-31, after a 75% drawdown. Yahoo reported:

Purchases: 4,363,572 shares / 21 transactions · Net Shares Purchased +3,546,185 · % Buy 12.3%

Read naively that is insiders accumulating into weakness — a golden flag under analysis_notes.md §6.3. The truth was the exact opposite: zero open-market purchases in the entire dataset back to May 2025, against ~$400M of CEO sales in June 2025 alone and metronomic monthly director selling all the way down.

The signal wasn't weak. It was inverted. This is worse than missing data, because it reads as confirmation.

How to avoid it

Never use the insider_purchases summary. Always pull holder_type="insider_transactions" and read the transaction rows, checking:

  1. Price per share. $0.00 = grant/vest, not a purchase. A strike far below the current price = option conversion, usually followed by an immediate sale.
  2. The text/description column — "Stock Gift", "Conversion of Exercisable Derivative", "Sale" vs. an actual open-market "Purchase".

Open-market insider buying is rare enough that when it's real it's unambiguous: cash paid at or near the prevailing market price. If you can't see that, it didn't happen.

Related

[[principle-primary-source-beats-vendor]] — same family. The authoritative source is the Form 4 on EDGAR, including its footnotes (which also carry 10b5-1 designation, a field Yahoo drops entirely — so "was this a pre-scheduled sale?" is never answerable from Yahoo alone).

History

  • 2026-07-31 — found during the RBLX analysis, where it would have flipped a red flag to a golden one.