(ShareCast News) - A bid from National Grid for US electricity-transmission company ITC Holdings Corp.is unlikely according to the Financial Times's Alphaville blog.According to a report published on Monday, the American outfit was working with financial advisers to seek potential buyers.The news sent ITC stock 9.27% higher to $36.88 by the close of trading after registering the largest intra-day jump in a decade.National Grid and Spain's Iberdrola were among the firms which were said to be considering an acquisition.However, while Alphaville was confident that National Grid was indeed participating in the process - which had kicked off a week ago - it's balance sheet and the fact that National Grid has only just appointed a new chief executive officer did not make an approximately $7bn deal "look very easy"."So. If National Grid's involved ... It's much more likely to be in there to look at the numbers of a rival, rather than to launch an offer," Alphaville said.As of 13:19 shares in National Grid were higher by 0.54% to 931.6p.