Fidelity Investments and T. Rowe Price more than doubled their stakes in Snap in the month after the company went public, buying around $500 million of stock between them, an analysis of SEC filings and online portfolio reports show. As a result, the two funds appear to have maintained their pre-IPO status as the biggest mutual fund investors in Snap.

That confirms what the funds have said about their reason for investing in private tech firms: to build a big position with the intention of holding for a long period of time. Having a relationship with the company before it goes public can also help them get a larger allocation of stock in the IPO.