PVH Corp. (NYSE:PVH), which owns brands including Calvin Klein and Tommy Hilfiger, today announced its plans to buy Warnaco Group (UNKNOWN:WRC.DL), which works under brands including Calvin Klein underwear, Speedo, and Olga.

The deal is expected to close in early 2013. Warnaco shareholders would get $51.75 in cash, as well as 0.1822 shares of PVH common stock, for each share of Warnaco. The merger would create a company with more than $8 billion in pro forma revenue, according to the companies.

PVH CEO Emanuel Chirico is excited about reuniting "the two largest apparel categories for Calvin Klein -- jeans and underwear," in a move he praised as encouraging for the growth of the brand.

According to the press release, the purchase price gives Warnaco a market cap of $2.9 billion, or a 34% premium to the last closing price of the stock.

The boards of directors of both companies have unanimously recommended that shareholders approve the transaction. Shares of PVH were up more than 15% on the news, while shares of Warnaco spiked more than 35%. 

Despite this, two law firms -- Briscoe Law Firm and Powers Taylor, LLP -- announced they would be launching an investigation into the acquisition. The investigation hinges on the question of whether "Warnaco shareholders are receiving adequate compensation," saying that the firms "believe that the transaction may undervalue Warnaco stock."