Eniac Ventures, a firm that backs early-stage mobile startups, is announcing that it has raised $55 million for its third fund. That's a big step up from its $12.9 million second fund — to say nothing of the first, $1.6 million fund that it announced back in 2010. Partner Hadley Harris told me that Eniac will continue to focus on seed-stage deals, and it plans to "lead or co-lead" the deals with initial checks averaging $500,000. The "majority" of the fund will be used to make follow-on investments in those companies. Founded in 2009 and based in both New York City and San Francisco, Eniac has now backed more than 60 startups. When I asked which ones are the most valuable, Harris replied that many of the most successful ones are still independent and private (and therefore not disclosing valuations). He did, however, point to recent successes like TapCommerce's acquisition by Twitter and Vungle's $17 million funding. More recent news from the portfolio includes Boxed raising $25 million, Glide raising $20 million, and Elevate being named Apple's free app of the year. (Through acquisitions, Eniac also has stakes in Airbnb and SoundCloud.) Oh, and not that speed is everything, but analysis from CB Insights last year found that among "micro VCs," Eniac's startups raise Series A's the fastest after the seed round. (Whether or not Eniac still counts as a micro VC with the new, bigger fund is debatable apparently.) The firm has been focused on mobile from the beginning, but Harris noted that this can also mean startups building Internet-connected wearables and other gadgets — as he put it, Eniac's definition of mobile-first includes "any company whose vision is based on the fact that people are constantly connected to the Internet." Harris said Eniac had initially targeted $50 million for the oversubscribed fund. The firm says investors in the fund include "prominent family offices, financial institutions, and ... a Top 10 university endowment." Besides Harris, Eniac's four partners include Nihal Mehta, Vic Singh, and Timothy Young. Harris described the team's strategy as "a swarm approach," where all partners can work with startups in the portfolio. By the way, I'm pretty sure Harris is the one on the far right in the team photo above. Don't ask me about the tractor, though.