Updated: Four firms that ranked among the top 10 most active U.S. venture firms in each of the first three quarters of 2008 didn’t make the top 10 list in the fourth quarter of last year, according to new Thomson Reuters’ data. It’s a notable bunch, too; those who slowed down are Kleiner Perkins and Sequoia Capital, along with InterWest Partners and Venrock Associates.

In the fourth quarter, Kleiner backed 11 companies, down from 26 in the third quarter; InterWest backed 13 companies, down from 17 in Q3; Sequoia backed nine companies, down from 19 in Q3; and Venrock invested in 13 companies, down from 18 in the third quarter.

Lots of other firms pulled back, too, including the two most active firms in the industry for all of 2008: Draper Fisher Jurvetson and New Enterprise Associates. DFJ backed 22 companies in the fourth quarter after investing in 40 in the previous quarter, while NEA backed 15 companies in the fourth quarter, down from 24 in third quarter.

Some VCs say the decline in Q4 numbers doesn’t indicate that they have slowed down. “There has been no change in strategy or market-facing activities at Venrock,” Ray Rothrock, a partner at Venrock, told me yesterday. “Deal flow is strong. I think it’s a coincidence [that Venrock’s deal numbers declined in Q4].”

Sequoia—which told its portfolio company CEOs in October to brace for a serious downturn— isn’t conceding that it has slowed its pace, either. When my editor, Larry Aragon, asked Michael Moritz in mid-November if his firm was making fewer investments, Moritz replied that “our doors are as wide open as ever.”

Meanwhile, Kleiner’s John Denniston tells me he doesn’t have a comment about whether or not the firm is taking a more measured approach to investing in this economy.

Only the GPs ultimately know whether they’re intentionally applying the brakes. Either way, given what looks to become a very prolonged recession, I’d guess the rest of the industry’s most active investors will follow their lead soon enough.

Speaking of, here’s a list of who did the briskest deal-making in 2008, according to preliminary Thomson Reuters data.

Update: Full MoneyTree data was released early Saturday morning. Here you go:

• National data spreadsheets, including sector-by-sector investing.
• Regional data spreadsheets
• Top Ten Deals – 2008
• Top Ten Deals — Q4 ’08
• Press release

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