Share Dilution From an ATM Offering

Worked example of cumulative ownership dilution from a daily at-the-market share offering, with a checkpoint table.

Editorial review required before launchBuild edition: September 2026Sources and limits below

A daily at-the-market (ATM) program issuing 5,000 shares a day for 180 days against a 10,000,000-share base dilutes existing holders by about 8.26% by the end of the program, before counting any use of the roughly $4,500,000 raised. This is an illustrative program size, run through the site's real ATM-simulation formula.

Cumulative ATM dilution over time
DayCumulative shares issuedCumulative dilution
1575,0000.74%
30150,0001.48%
45225,0002.2%
60300,0002.91%
75375,0003.61%
90450,0004.31%
105525,0004.99%
120600,0005.66%
135675,0006.32%
150750,0006.98%
165825,0007.62%
180900,0008.26%

Why ATM dilution is gradual

An ATM program sells new shares into the market over time rather than in one offering, so dilution accumulates day by day instead of all at once. Cumulative dilution percent equals shares issued so far divided by the resulting total share count, the same denominator logic as a single offering.

This models a hypothetical, user-entered program size. It is not a specific company's actual ATM prospectus or issuance schedule; check the company's S-3 and prospectus supplement filings for the real program terms.

Open the ATM simulator in the workspace

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