During the depths of the global financial crisis, Colm Kelleher was instrumental in keeping Morgan Stanley afloat — an experience the Irish finance veteran will draw on as he oversees the biggest bank takeover since those tumultuous days.

“He was on the phone with regulators all the time,” recalled John Mack, Morgan Stanley’s chief executive at the time.

“He was the point person, working with the whole US Treasury group and guys in Washington to make sure that ourselves and the likes of Goldman Sachs survived and the whole bank run was blocked.”

As chief financial officer, Kelleher was responsible for taking decisions that were unpopular at the time to make sure there was enough liquidity within the bank to avoid the fate of rival Lehman Brothers, which collapsed in ignominy.

A decade and a half later and Kelleher is once again centre stage in a banking crisis — this time as chair of UBS, the Swiss lender that agreed to rescue its fierce rival Credit Suisse two weeks ago.

The 65-year-old, who prefers to operate in the shadows, has been thrust into the spotlight after orchestrating the first ever union of two global systemically important financial institutions.

UBS’s $3.25bn rescue of Credit Suisse will create the world’s fourth largest bank — with 120,000 staff and $5tn of assets under management — and by far the most important financial institution in Switzerland.

But the drama did not stop there. Just 10 days after agreeing the takeover, Kelleher replaced UBS’s chief executive, Ralph Hamers, with the Dutchman’s predecessor, 62-year-old Sergio Ermotti, who ran the bank between 2011 and 2020.

It was a sign of Kelleher’s ruthless streak, but a decision he told journalists was down to needing to have in place “the better pilot [for] this next voyage of UBS”.

The moves have cemented Kelleher’s position as Europe’s most powerful banker — a far cry from growing up as one of nine siblings in Cork.

After graduating from Oxford university and training as an accountant, Kelleher joined Morgan Stanley’s London office in 1989, initially working on the bank’s fixed income desk before becoming head of global capital markets.

He was spotted by Mack, who tried to bring him across to Credit Suisse when he was named CEO of the Swiss bank in 2001. But Kelleher resisted the overtures and instead moved to New York with Morgan Stanley.

After Mack returned to Morgan Stanley in 2005, he made Kelleher his CFO in 2007.

In just a few months in 2008, Kelleher aggressively ran down the bank’s balance sheet and tripled its cash position.

“During the financial crisis Colm was pivotal to Morgan Stanley’s survival,” said Huw van Steenis, global head of strategy at Oliver Wyman who worked at the bank with Kelleher for 15 years.

“His steeliness and financial savvy was the perfect compliment to John’s hustle to save the firm.”

After Mack left in 2010, Kelleher missed out on the top job to Australian James Gorman. But the pair worked closely over the following decade, cutting back the investment bank and refocusing the business on wealth management — a strategy he will lean on again while integrating the Credit Suisse business.

While Kelleher’s gregarious nature, dry sense of humour and booming laugh made him popular among Morgan Stanley colleagues, his offhand comments occasionally caused offence.

He fell out with Paul Taubman, his co-head of Morgan Stanley’s institutional securities group, in 2011. Taubman later left the bank to start his own advisory boutique, PJT Partners.

After retiring from Morgan Stanley in 2019, Kelleher took a year out to spend time with his wife and three children, learn to play the piano and walk 500 miles of the Camino de Santiago, a popular pilgrim route across northern Spain, when he raised more than $300,000 for a student sponsorship programme.

The donor list — which offers an insight into Kelleher’s network — includes a host of high-profile bankers, such as Bob Diamond, António Horta-Osório, Bill Winters, Ross McEwan and Joe Perella, as well as investment management executives Manny Roman, Rick Rieder and Michael Hintze.

When Kelleher took over from German former central banker Axel Weber as chair of UBS a year ago, he not only inherited his predecessor’s office but also his apartment, just a few blocks from the bank’s Zurich headquarters.

Since hitching up at UBS, Kelleher has kept his management team on their toes. One senior executive said this was down to his training as an accountant.

“He actually does know his stuff — he doesn’t like anything fluffy, no BS,” the person said. “Don’t go into a meeting unprepared — he is a serious person, he has been through a crisis before.”

Kelleher made global headlines in November when a joke he made on stage about pandering to China at a high-profile Hong Kong financial forum was reported as UBS turning its back on the West.

“We’re not reading the American press, we actually buy the [China] story,” he said, following earlier remarks by the vice-chair of the China Securities Regulatory Commission about international media giving inaccurate accounts of what was going on within the country.

Kelleher will be keen to avoid similar mis-steps as he draws on his experience of the financial crisis to ensure the rescue of Credit Suisse is a success for UBS.

“This is the biggest single financial transaction since 2008,” he said this week. “I would argue it’s bigger than any deal that was done in 2008.”

Additional reporting by Stephen Morris