The Mexico-headquartered company issued 19,633,430 shares, raising around £220m, to First Eagle Investment Management, which already holds a 1.6 per cent stake.
Changes to FTSE listing regulations now require companies to maintain a minimum freefloat of 25 per cent and the new shares issued will allow Fresnillo to remain on the FTSE index.
The £220m raised will be used for general corporate purposes and working capital needs, the company said.
Fellow FTSE-listed miners ENRC and Ferrexpo still need to meet the new regulatory limit.
ENRC, which currently has an 18 per cent freefloat, is the subject of a takeover approach by a trio of its founding shareholders and the Kazakh government, who have until 17 May to make a formal offer to take the company private.