After the announcement of the $4 billion acquisition of Virgin America by Alaska Air, Virgin founder Richard Branson expressed his disappointment in the move, saying there was nothing he could do to prevent it.

"I would be lying if I didn't admit sadness that our wonderful airline is merging with another," Branson wrote Monday in a post on Virgin's website.

"Because I'm not American, the US Department of Transportation stipulated I take some of my shares in Virgin America as non-voting shares, reducing my influence over any takeover. So there was sadly nothing I could do to stop it."

According to Department of Transportation regulation, only 25% of an airline based in the US can be owned by a foreign entity or non-US citizen, meaning Branson's control as a British citizen was limited.