Co-founder James Watt said Christmas had come early for the Aberdeenshire craft brewer after investors snapped up the last of the 42,000 shares available in its third Equity for Punks scheme.
The campaign launched in June and saw £1m worth of shares sold in the first 24 hours. BrewDog, which also operates 13 bars, had initially set a £4m target, but extended that by £250,000 in November to keep pace with demand.
The shares were offered at £95 each.
Mr Watt said: "The response to Equity for Punks this year has been absolutely epic. Closing early only goes to show just how passionate and evangelic[al] our fans are."