UPDATE 2-VeriSign Q3 profit narrowly beats estimates

* Q3 adj EPS $0.33 vs $0.32 est

* Revenue up 5 pct

* Sees Q4 rev flat to up 2 pct sequentially

* Shares down 5 pct (Recasts; Adds conference call details, share movement)

Nov 5 (Reuters) - VeriSign Inc (VRSN.O) swung to a third-quarter profit, helped partly by continued strength in its core businesses, but its fourth-quarter revenue forecast fell below Wall Street estimates, sending its shares down 5 percent in post-market trade.

The Internet security and naming services company forecast fourth-quarter revenue of $258 million to $262 million, or flat to up 2 percent sequentially.

Analysts expect revenue of $264.2 million, according to Thomson Reuters I/B/E/S.

The company expects fourth-quarter adjusted operating margin of 38.6 percent to be in line with that of the third quarter.

Net names added to the domain net base in the fourth quarter are expected to be slightly up from the third quarter to $1.5 million, Chief Executive Mark McLaughlin said on a conference call.

VeriSign's naming services segment is the authoritative directory provider of all .com, .net, .cc, .tv, .name and .jobs domain names.

Revenue from VeriSign's core businesses of naming and authentication services rose 6 percent to $257 million.

Since 2007, the company has been focussing on divestitures, selling its slower-growing units to focus on its core businesses.

"With the majority of the divestures behind us, there will be less noise and greater consistency in cash flow in 2010," Chief Financial Officer Brian Robins said on the call.

For the third quarter, the company earned $54 million, or 28 cents a share, compared with a loss of $201.1 million, or $1.04 a share, a year ago.

Excluding items, for its core businesses, VeriSign earned 33 cents a share.

Revenue rose 5 percent to $258 million.

Analysts were expecting earnings of 32 cents on revenue of $258.8 million, according to Thomson Reuters I/B/E/S.

Shares of the Mountain View, California-based company were down 5 percent at $22.85 in trading after the bell. They closed at $24.00 Thursday on Nasdaq.

(Reporting by Manasi Phadke in Bangalore; Editing by Anil D'Silva)