Michael Klein, the former Citigroup Inc. investment banker who runs his own M&A firm, nailed his first major deal of 2016 as one of the lead advisers for IHS Inc. in its acquisition of financial data firm Markit Ltd.

Klein, who previously served on the board of Englewood, Colorado-based IHS for almost a decade, has used the connections he made in more than two decades rising through the ranks at Citigroup to win roles on some of the most high-profile deals of the last few years.

In December, New York-based M Klein & Co. was listed first among advisers to Dow Chemical Co. on its merger with DuPont Co., the largest-ever chemicals deal that is expected to create a $130 billion company. In 2012, Klein was appointed as an independent adviser on Glencore Plc’s merger talks with Xstrata Plc, working as a go-between to Chief Executive Officers Mick Davis and Ivan Glasenberg and helping the two men come to terms, people with knowledge of the deal said at the time.

His success is part of a wave of so-called boutique investment banks that are winning business away from bulge brackets, such as Goldman Sachs Group Inc. and Morgan Stanley, as high-profile employees quit to start their own firms.

Robey Warshaw, created by ex-bankers from Morgan Stanley and UBS Group AG, is ranked 17th by total deal value, advising on $214 billion in deals in the last 12 months, according to data compiled by Bloomberg. Greenhill & Co., founded in 1996 by former Morgan Stanley banker Robert Greenhill, is No. 30 with $61.3 billion.

Before it's here, it's on the Bloomberg Terminal. LEARN MORE