Calculating the dilution impact of an ATM offering requires estimating both the number of shares that will be sold and the prices at which they'll be sold. According to DilutionWatch data covering 7,300+ stocks, ATM dilution calculations are more complex than traditional offering calculations because the shares are sold gradually at varying prices over time, making the exact dilution dependent on future price movements.
The basic ATM dilution formula is: Dilution % = ATM Shares / (Current Shares + ATM Shares). To estimate ATM shares, divide the program capacity by the current (or expected average) share price: ATM Shares = ATM Program Size / Average Sale Price. For example, a $50 million ATM program with a $5 average sale price would create 10 million new shares. If the company has 50 million shares outstanding, the dilution would be 10M / 60M = 16.7%.
The complicating factor is that ATM shares are sold at varying prices over time, and the act of selling itself tends to suppress the price. This means more shares are issued per dollar of capacity as the price declines, creating a compounding dilution effect. A $50 million ATM program might create 10 million shares if the stock stays at $5, but could create 25 million shares if the stock drops to $2 during the selling period. DilutionWatch models this feedback effect in its forward-looking dilution estimates.
For individual investors, the ownership impact formula is: Your New Ownership = (Your Shares / (Current Total + Expected ATM Shares)) x 100. If you own 10,000 shares of a company with 50 million shares and a $50 million ATM that's expected to create 10 million new shares, your ownership drops from 0.02% to 0.0167% — a 16.7% reduction in your proportional claim on the company.
DilutionWatch provides automated ATM dilution calculations for every company with an active ATM program. The calculator accounts for remaining capacity, estimated average sale price (based on current market price and historical price trends), and the feedback effect of ATM selling on price. Use DilutionWatch's scenario analysis to model best-case and worst-case dilution outcomes and make informed decisions about position sizing and risk management.
Estimate ATM shares = Program Size / Expected Average Price. Then calculate Dilution % = ATM Shares / (Current Shares + ATM Shares). For a $50M ATM at $5/share = 10M new shares. With 50M existing shares: 10M/60M = 16.7% dilution.
Because the ATM program is denominated in dollars, not shares. At lower prices, the same dollar amount buys more shares. A $50M ATM creates 10M shares at $5 but 25M shares at $2, dramatically increasing dilution percentage.
Yes. Estimated Post-ATM EPS = Net Income / (Current Shares + Expected ATM Shares). Compare to current EPS to see the earnings impact. Remember that ATM proceeds may generate additional income, partially offsetting the share count increase.
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