The surge follows reports in the US press that EchoStar, the second-largest pay-TV group in the US, has scrapped its plans to challenge News Corp's bid.
EchoStar's decision came when its first offer was refused by GM because it feared that a large anti-trust investigation would likely ensue.
It has also been reported that GM told the smaller satellite TV provider that it had chosen News Corp's offer for Hughes, the GM division that owns DirecTV.
If a deal between GM and News Corp goes ahead, News Corp will control a company worth $50bn (£35.7bn), born out of a reverse takeover of Hughes by Sky Global Networks, parent of BSkyB.
Hughes shareholders would own more than 50% of the combined company and GM would receive around $7bn (£5bn) in cash and notes in return for its 30% stake in Hughes. However, News Corp will have operational control of the company.
News Corp will combine DirecTV with its European and Asian operations, which include BSkyB in the UK; Star TV in Asian markets including India, China, Taiwan and Hong Kong; and Sky PerfecTV in Japan.