Fortune has learned that Sacca’s firm, Lowercase Capital, has reached out to investors about raising its first-ever later-stage fund. It has not yet set a formal target, which likely could be anywhere from around $40 million to upwards of $100 million.

Lowercase historically has been a seed-stage investment firm, making very early bets on such companies as Instagram, Stripe, Uber and Twitter (TWTR). It also has raised relatively small funds, meaning that it has been virtually unable to participate on follow-on rounds for its fastest-growing portfolio companies (outside of occasionally creating special purpose vehicles, as it did most notably with Twitter). Not only because of cash limitations, but also because investing $5 million or $10 million out of a $34 million fund would completely distort diversification.

So it is beginning to raise what it refers to as an Ownership Fund, which will participate in certain follow-on rounds for existing portfolio companies, plus select later-stage deals for companies that Lowercase has not already backed. Ownership Fund will not collect management fees until capital is called, and any investment in an existing portfolio company will be married with a smaller co-invest out of the flagship seed-stage fund at the same valuation (so that LPs don’t feel funds are being played off of each other).

Speaking of that flagship fund, Lowercase also is just weeks away from holding a final close on its latest edition. TechCrunch previously reported that the firm is raising $25 million, but my understanding is that it will end up closer to $40 million. This will be the first Lowercase fund not led by founder Sacca, who is transitioning into a chairmanship role. There had been some early talk that Sacca — a onetime Google (GOOG) executive — was planning to walk away entirely, but he will work with existing portfolio companies and provide a second set of eyes to recently-promoted managing director Matt Mazzeo (who will take all first meetings, view all incoming deal-flow, etc.).

No word on when Lowercase is hoping to close the Ownership Fund. Sacca declined comment, citing regulatory restrictions.

Sign up for Dan Primack’s daily email newsletter on deals and deal-makers: GetTermSheet.com