NEW YORK/LONDON (Reuters) -When Novo Nordisk CEO Mike Doustdar learned in late September that Metsera had accepted a $7.3 billion rival bid from Pfizer, he was not ready to give up just yet on the company and its portfolio of experimental obesity drugs.

Facing pressure to show results after taking the helm of the Danish drugmaker in August, Doustdar had already made five increasingly costly offers for Metsera, according to U.S. securities filings and court documents.

Yet he decided to push ahead with an unconventional deal structure worth about $10 billion, some five times what Doustdar's predecessor had been willing to pay in January, according to three sources briefed on the process.

The offer called for Novo to pay billions of dollars upfront for a stake in Metsera, and could have left it without full control over Metsera's novel obesity drug pipeline if antitrust regulators opposed it. In the end, the move prompted Pfizer to offer more money to finalize its own deal.

"I don't blame them for looking, but I do think it was always going to be very tricky to get this over the line," Berenberg analyst Kerry Holford said of Novo's efforts to land the deal.

NEW TOLERANCE FOR RISK

Doustdar showed a willingness to take new risks to make Novo more competitive with rival Eli Lilly by being faster and more aggressive, said two of the sources. Lilly has overtaken Novo's once-dominant position in the highly lucrative U.S. weight-loss market.

Some investors and analysts welcomed the change in tone. Erik Berg-Johnsen, portfolio manager at Novo shareholder Storebrand Asset Management, told Reuters the company was showing "a more clear sense of urgency" to improve its fortunes.

Jyske Bank analyst Henrik Hallengreen Laustsen, who has a "buy" rating on Novo, said Doustdar's move for Metsera was an "important signal" it would not be passive.

"They attack the market rather than having to defend themselves," he said.

Others questioned whether Doustdar went too far. The bidding war coincided with increasing governance concerns, alongside a board of directors' shake-up that will hand unprecedented control to the company's top shareholder.

"It felt like this is a lot of shooting from the hip," said BMO Capital Markets analyst Evan Seigerman, who has a hold rating on Novo, adding the company has other issues to solve.

"You have expected pricing headwinds. You have Lilly really snapping up market share, and it feels like Novo is on a ship that just has gone so far off path that it's hard to right that ship."

Berenberg's Holford said Novo needs to look for deals to bolster its drug pipeline given previous relative inaction in mergers and acquisitions, as well as looming patent expiries for semaglutide, the active ingredient in Wegovy and Ozempic.

Novo did not respond to a request for comment. Metsera declined to comment.

NOVO CEO WAS CONFIDENT OF FTC CLEARANCE

Doustdar has defended Novo's pipeline of experimental weight-loss drugs, but said an aggressive acquisition strategy was critical to keep up with a market estimated by some analysts to reach $150 billion by early next decade.

"When you have an ambition to go to hundreds of millions of people and treat them, then no pipeline is broad enough," the CEO said during a call with industry analysts last week.

The final Novo bid structure front-loaded higher payments in exchange for a 50% stake, but delayed the timing for gaining operational control, according to the securities filings. 

Doustdar was convinced the proposed deal would hold up under review by the U.S. Federal Trade Commission.

It didn't go as planned. The FTC contacted Metsera to warn it that the Novo deal could pose antitrust risks, Metsera said in a November 7 press release announcing it had accepted a sweetened offer from Pfizer. Novo then pulled out of the race.

"Every transaction has a price," said Marcus Morris-Eyton, portfolio manager for European and global growth equities at Novo shareholder Alliance Bernstein, "and we are pleased to see management exercising financial discipline if they felt the price had become too high."