They've jumped through the last of the procedural hoops so (NASDAQ:BKNG) and Kayak (NASDAQ: KYAK) have set the date for their merger. The online travel agent and the travel metasearch engine have scheduled the closing date for May 21 with Kayak shareholders needing to submit how they want to receive their consideration by 5 p.m. Eastern time on May 14.

Priceline is buying Kayak for $1.8 billion in cash and stock and Kayak investors may receive either cash or stock valued at $40 per share, subject to a collar mechanism where they'll get that price so long as Priceline's shares trade between $571.31 and $698.27 for 30 days prior to two days before the closing. If the average price is above $698.27 or below $571.31, Kayak investors will receive less or more shares depending on how the stock traded.

Priceline's stock closed trading yesterday at $737.50 per share and has regularly been above the upper limit of the threshold for the past month.

The final number of shares to be issued on a fully diluted basis will range between approximately 1.9 million and 2.3 million shares and options at closing.