BOUTIQUE BONANZA: 3 small Wall Street firms grabbed big roles on the Pfizer-Allergan mega-deal

Pfizer has agreed a deal to combine with Allergan in a $160 billion transaction that will be among the biggest deals of all time.

And three small Wall Street firms are in on the action.

Guggenheim Partners, Centerview Partners and Moelis & Company are all advising Pfizer on the transaction alongside Goldman Sachs.

The four banks will split more than $100 million in deal fees, according to Jeffrey Nassof of M&A consulting firm Freeman & Co.

JPMorgan and Morgan Stanley are advising Allergan on the transaction.

This isn't the first time the three firms have landed big roles on huge transactions.

Guggenheim previously advised on the giant Verizon-Vodafone transaction in 2013, where the US telecoms company acquired the stake it didn't already own in Verizon Wireless for $130 billion.

Centerview, which is led by Blair Effron, has worked on a pantry's worth of giant food and beverage deals: Anheuser-Busch InBev, Kraft, HJ Heinz.

Boutique banks have landed roles on some of the biggest M&A deals of 2015. In the wake of the financial crisis, boutiques' share of M&A has substantially increased, into the high teens on a percentage basis.