Washington-based law firm Wilmer Cutler Pickering and Boston-based Hale & Dorr have announced their merger, which will create one of nation’s largest law firms. Both of these firms were mid-sized major firms that compete with larger multinational firms, so the merger makes some sense in that the combined firm will be on a similar footing to those larger firms.
In that connection, Professor Ribstein over at Ideablog has interesting post that on the merger that points out that it could be a good thing for some big firms to grow even bigger:

[L]egal ethical rules constrain law firms from getting as big as they need to get. In particular, restrictions on non-competition agreements prevent firms from binding lawyers to the firm. These restrictions also constrain firms from compensating lawyers in ways that get them to focus on the long-term interests of the firm.
In other words, without ethical rules, big law firms would get even bigger, and more independent from clients. The result might be that lawyers would be more, rather than less, loyal to the long-term interests of clients and society. Ethics can be viewed as yet another product of free markets.