UBS' former head of energy banking, Stephen Trauber, set up shop in Citigroup Inc.'s Houston office at the start of the year as global head of energy investment banking with 19 former colleagues in tow. News of Trauber's hiring was accompanied by a Wall Street Journal report that Citi would pay him up to $30 million over three years, which Trauber and Citi denied. Whether that figure was accurate or not, it's clear that Citi made a heavy bet on energy. And Trauber, for one, is convinced it is paying off.

"We've done over 100 transactions year-to-date," he says, consisting mostly of equity financings, but including a smattering of M&A deals as well. According to Dealogic, Citi advised on 11 oil and gas M&A transactions valued at about $20 billion as of mid-October, ranking it No. 6 in the oil and gas league tables. Citi also ranked sixth at the end of 2010, advising on 14 deals worth about $34.3 billion.

Soon after moving, Trauber, 49, worked alongside Citi director ­Claudio Sauer, to advise Houston refinery Frontier Oil Corp. on its $2.9 billion sale to Dallas counterpart Holly Corp. Late last month, longtime client Anadarko Petroleum Corp. tapped Trauber when it put its Brazilian assets on the block -- a sale that The Deal Pipeline reported could net $4 billion to $6 billion in proceeds. Jerry Schretter, who joined Citi from UBS with Trauber, is leading that mandate alongside Morgan Stanley and Houston-based Scotia Waterous. ­Michael Jamieson, another UBS veteran, is teaming with Sauer to advise Houston's Boardwalk HP Storage Co. LLC on its $550 million acquisition of the natural gas storage facilities of Enterprise Products Partners LP, announced in October.

Citi has also been busy working on initial public offerings in the energy sector. It is joining Bank of America Merrill Lynch, Goldman, Sachs & Co. and Credit Suisse Group to underwrite the planned $1.15 billion IPO of energy services provider Frac Tech International, announced in September. Citi and BAML advised ­Temasek Holdings Pte. Ltd., Chesapeake Energy Corp. and RRJ Capital on their leveraged buyout of Frac Tech in April and provided $1.7 billion in financing for the LBO. Citi was also named a lead underwriter on Houston oilfield services company Platinum Energy Solutions Inc.'s planned IPO, targeted at up to $300 million­ -- announced in late September.

Trauber and his team's arrival increased the size of Citi's Houston corporate and investment banking effort to about 50. Citi has since hired 10 more bankers for the office, including Mark Hobbs from UBS, who joined in May as global head of downstream. "Bringing the UBS team gave immediate breadth and scope to our practice," Trauber says. And he predicts the group will remain busy as more overseas buyers gain comfort in snapping up U.S. targets. Citi "signed up a deal earlier this week with a big Chinese player in North America," Trauber told us back in mid-October. All in a day's work for Citi's $30 million man.