Lassonde said he recently purchased 2 million Prime shares through the TSX Venture Exchange, taking his direct and indirect holdings to 11.85%.
Prime is focused on its Los Reyes project in Mexico's Sinaloa state, where it last year updated the resource to a measured and indicated 633,000 ounces of gold and 16.6 million ounces of silver, or 833,082oz gold-equivalent, using a 0.22g/t cut-off.
The company last year accelerated its option agreement over Los Reyes and said in January it had one final US$1 million payment due during July to cancel Vista Gold's royalties and back-in rights.
Prime began a 15,000m drilling programme at Los Reyes in December.
Trinity Capital Partners, including Lassonde, were participants in Prime's June 2020 C$10 million raising, which was priced at 50c per unit.
Prime shares (TSXV: PRYM), which were trading about 50c 12 months ago, hit a one-year high intraday of $2.80.
They closed up 6.3% to $2.70, capitalising it at $232 million (US$181 million).