Union Square Ventures, the New York-based venture capital firm that has backed such companies as Twitter TWTR , Tumblr and Etsy ETSY , has raised $166.8 million for its fourth early-stage fund, according to a regulatory filing.

This is basically the same amount of capital USV raised for its third fund in 2012, at which time it simultaneously raised a $175 million “opportunities fund” for later-stage opportunities. It is unclear is USV has yet raised a follow-on for that vehicle.

USV was founded in 2003 by veteran venture capitalists Fred Wilson and Brad Burnham, and now features five general partners (the others are Albert Wenger, John Buttrick and Andrew Weissman). Its overall internal rate of return (IRR) since inception is a whopping 60.85 through the end of last November, according to documents published by one of its investors:

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Last month, I interviewed Wilson in Los Angeles, as part of the Upfront Summit. During that conversation, he acknowledged that USV is beginning to think about generational succession planning, but there are no partnership changes apparent on the new fund.

Wilson declined to comment on the new fund due to SEC marketing restrictions (which suggests there are some outstanding commitments which have not yet closed, or perhaps it’s related to a new “opportunities” fund).

Three updates:

1. This doesn’t quite appear to be a final close, but rather the institutional piece, with upcoming individual commitments bringing the total to $175 million.

2. The SEC filing lists the same five general partners as were listed the last time around, but an LP tells me that there has been a switch when it comes to the “managing partner” roles. Rather than firm co-founders Brad Burnham and Fred Wilson, the managing partners are now Albert Wegner and Andy Weissman. “It basically means that if we need to talk or complain about something, we call Albert or Andy now” the LP says. “I think not being managing partner sounds like a better job.”

3. There is no opportunity fund being raised this time around, apparently because the existing vehicle has plenty of dry powder.