Diluted shares and the treasury stock method
By SuperdayReps · Michigan Ross Undergrad | Wharton MBA · ex-Citi | ex-Greenhill · Former Head Mentor at a Leading IB Prep Service
5 min read · updated July 8, 2026
Ask how many shares a company has and you will get two different answers, both correct. There is the number of shares that exist today, and there is the larger number that would exist if everyone holding a claim on new shares cashed it in. Valuation, earnings per share, and every accretion/dilution question turn on the second one, so you have to know how to get from the first to the second.
Basic versus diluted shares
Basic shares outstanding is the straightforward count: the shares that exist and trade right now. Diluted shares outstanding adds the shares that would be created if every in-the-money option, warrant, and similar claim were exercised. Diluted is always greater than or equal to basic, never less.
The reason the gap exists is that companies hand out claims on future shares. When those claims convert, the share count grows and each existing owner holds a slightly smaller slice of the same company. That shrinking of ownership is what "dilution" means.
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Frequently asked
- What is the difference between basic and diluted shares?
- Basic shares outstanding is the count of shares that exist and trade right now. Diluted shares adds the shares that would be created if every in-the-money option, warrant, and similar claim were exercised. Diluted is always greater than or equal to basic, and it is the count valuation and EPS run on.
- How does the treasury stock method work?
- It assumes the company takes the cash option holders pay to exercise and immediately uses it to buy back its own shares at the market price. Only the leftover, unbought shares dilute. The formula is net new shares equals N times the quantity P minus K, divided by P.
- Why are out-of-the-money options excluded from the diluted share count?
- Because no rational holder exercises an option whose strike sits above the market price. If the strike is 30 and the stock trades at 25, exercising means paying 30 for something worth 25. Those options are out of the money and contribute zero dilution until the stock price recovers above the strike.
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