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  1. Home
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  3. Trading Terms

Open Market Purchase

M
Marcus Thorne
Last Updated: January 5, 2026
Plain English Definition

An open market purchase occurs when an insider buys company stock on a public exchange (NYSE, NASDAQ, etc.) at the current market price, just like any other investor. This is transaction code "P" on Form 4 filings.

The Trader's Take

The Signal

Open market purchases are among the strongest bullish signals. When executives buy with their own money at market prices, it demonstrates genuine conviction about the company's future.

The Noise

Small purchases for tax-loss harvesting or portfolio rebalancing are less meaningful than large purchases that increase position size significantly.

Actionable Insights

  • 1
    Focus on purchases that increase the insider's total position by more than 10%.
  • 2
    Compare the purchase price to recent trading ranges—buying near 52-week highs is more significant.
  • 3
    Look for cluster buys where multiple insiders purchase within the same month.

Regulatory Context & Context

Open market purchases must be reported on Form 4 within two business days. These transactions are subject to Section 16(b) short-swing profit rules, meaning the insider cannot sell for six months without forfeiting profits.

Common Misconceptions

Not all purchases are "open market"—some are grants, exercises, or other transaction types.

The size of the purchase matters more than the dollar amount—percentage of position increase is key.

Frequently Asked Questions

What transaction code indicates an open market purchase?

Transaction code "P" on Form 4 indicates an open market purchase.

How quickly must open market purchases be reported?

Form 4 must be filed within two business days of the transaction.

On This Page

Trader's TakeRegulatory ContextCommon MisconceptionsF.A.Q.

Related Intelligence

SEC Filings
Form 4
Trading Terms
Transaction Code P
Trading Terms
Informative Buy
Trading Terms
Cluster Buy

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