Shares of InterDigital Inc plunged 23 percent on Monday after Google's $12.5 billion Mobility Holdings buy sparked worries that the search giant may no longer be interested in the company's wireless patents.

In July, InterDigital said it was looking at a possible sale of the company and the Wall Street Journal later reported that Google might be in the race for its patents.

Google may have already lost its bid for the IDCC patents and is announcing a Plan B before anything else happens to IDCC; or may be Google prefers the Motorola patents over the IDCC patents, M Partners analyst Ron Shuttleworth said.

Interdigital makes most of its money from licensing its patented technology and from damages it wins in patent lawsuits.

Companies like InterDigital, with strong patent holdings, can force rivals to pay fees for using their technology or to form cross-licensing agreements.

The company holds and licenses around 8,800 patents that range from basic wireless telecommunications system designs and processes to increase network coverage to ways of extending battery life and making more efficient use of bandwidth.

Some other IDCC licensees such as Samsung Electronics, LG Electronics and HTC Corp, which are battling Apple's rising popularity, might buy the patents, said Shuttleworth.

He expects InterDigital, which has a market value of $3.44 billion, to fetch a $5 billion price.

Shares of the company fell $14 to $61.44 in heavy trading, making the stock the top percentage loser on Nasdaq.

(Reporting by Sayantani Ghosh in Bangalore; Editing by Saumyadeb Chakrabarty)