Just in time for the New Year, Riverbed Technology (RVBD) gets a present: a $19-per-share bid from hedge fund Elliott Management, which may well raise eyebrows and get other people interested.

This represents a 6% premium of Riverbed's closing price on Tuesday, but shares are already trading well above the $19 offer at $19.89 as of about 11 AM Eastern, up 11%, or $2.03.

It's possible that some information had been leaking into the market, as the stock had been creeping up in the last couple of months. Riverbed has been as low as $13.77 in the last year. Riverbed Technology was one of the Rayno Report's 2013 picks. (Disclosure: Of course, I no longer personally hold the stock.)

Some analysts on Wall St. say Riverbed was undervalued and the deal makes sense. It's also possible that the bidding is not over, as other players such as Cisco Systems or Juniper Networks may want to take a look. The share price, which is already trading above the offer, indicates that.

“I don't think the transaction gets done at $19, but the market is already saying that,” says Alex Henderson, an analyst at Needham & Co. “The stock is at a premium in the category, but I think this transaction is going to take a long time.”

Because the bid is essentially unsolicited -- read, “hostile” -- the Riverbed board will want to weigh it and then go out and get a better price. Riverbed has already issued this statement, saying “Riverbed is focused on creating value for all of our shareholders, and maintains an open dialogue with our shareholders, including Elliott.”

Riverbed, once a networking high flier that has struggled with stagnant revenues and a sinking share price over the last year, was a pioneer in the so-called WAN-optimization space, in which a combination of software and hardware is used to more efficiently make use of bandwidth when enterprises connect to service providers. It's stock rose as high as the low-40s in early 2011 and it had a market capitalization North of $6 billion.

Growth in the WAN optimization space has slowed in the past year, however, and Riverbed missed revenue on a few quarters. Some of its newer products did not take off to compensate for slower WAN optimization growth. But Riverbed is still considered a high-quality technology company with a good sales channel into enterprises, and that may be what attracted Elliott.

Even after the bid, the stock is still not unusually expensive, trading at a forward price/earnings ratio of 17. The company also has $433 million in cash on its balance sheet.

This may be why some analysts on Wall St. say the story may not be over.

(Discosure: No position in RVBD.)