Skadden, Arps, Slate, Meagher & Flom and Paul, Weiss, Rifkind, Wharton & Garrison have the lead roles on a $3.4 billion deal that will see China's two largest tavel-booking websites merge.

In a deal announced on Monday, Ctrip.com International Ltd. and Qunar Cayman Islands Ltd. agreed to combine through a share swap arrangement. Baidu Inc., Qunar's largest shareholder, will own 25 percent of Ctrip, while Ctrip will hold a 45 percent stake in Qunar.

The deal values Ctrip at $10.6 billion and Qunar at $5.2 billion. Both companies provide online flights and accommodations bookings and have a combined 70 percent market share of China's online trip-booking market.