It's not an April Fool's joke.
1) Both companies officially commented on the news.
2) They filled the appropriate paperwork with the SEC. Why face fraud charges over some April Fool's prank?
3) Tying into #2, the news affected the stock price/momentum of both companies during the trading day. People lost or made fortunes... for a gag?
Oh, yes, 25 million is a ridiculously low amount... but maybe this is it for SGI.