It took less than two full days of play for Warren Buffett to win his bet that no entrant in a Quicken Loans Inc. contest would predict the winner of each game in the three-week-long National Collegiate Athletic Association men’s basketball tournament.

Had someone been successful, his Berkshire Hathaway Inc. would have been responsible for paying a $1 billion prize as part of an insurance policy it sold to the lender.

Two upsets — Dayton’s defeat of Ohio State two days ago, and Mercer’s win yesterday against Duke — wiped out 99 percent of the entries. When Memphis defeated George Washington last night, the last of the perfect brackets was busted.

“While everyone loves an underdog, you could hear a collective groan around the office each time an upset happened,” Jay Farner, president and chief marketing officer of Quicken Loans said in an e-mailed statement. “We knew that meant a lot of the entrants had their brackets bust, and lost their opportunity at the billion dollars.”

The contest was announced in January and proved a publicity bonanza for Buffett, 83, and Quicken Loans founder Dan Gilbert. Print and broadcast media focusing on sports, business and general news have covered the contest and speculated about the probability of a winner emerging. Both companies declined to say how much the insurance cost.

Calculating the exact odds of a perfect bracket is impossible, because picking the winner of a game isn’t a random event like a coin flip, Buffett said. That’s especially true in the first round when the top-seeded teams almost always prevail.

Calculating Odds

“I charged a premium that was a reasonable amount above what I thought the odds were,” he told ESPN before the tournament began. “I had another guy at Berkshire Hathaway make his own calculation, independent of me, and we were in the same ballpark. But it was a pretty big ballpark.”

Submissions for the contest were limited to one per person and capped at 15 million entrants. The bracket challenge excluded the games that narrowed the field to 64 teams from 68. The round of 64 began two days ago in the single-elimination tournament.

Vee Sanford made a running shot off the backboard with less than four seconds remaining as 11th-seeded Dayton won 60-59 against No. 6 seed Ohio State. An even bigger upset came when third-seeded Duke lost 78-71 to Mercer.

Tweets mentioning Buffett’s likely avoidance of the payout proliferated on Twitter Inc.’s messaging service after Duke was knocked out of the tournament.

“Warren Buffett just lit a cigar with a one million dollar bill,” Jack Moore, a comedian, wrote in a post on the site. “He had it specially minted for the occasion.”

Insurance Policy

The odds of picking every winner correctly in a 64-team bracket are about 1 in 1 billion, assuming a contestant makes intelligent choices, Ezra Miller, a professor of math at Duke, wrote on the school’s website March 12. Given that probability and the number of entrants, the insurance policy should have cost more than $15 million, he said.

A winner would’ve been entitled to $25 million annually for 40 years, or an immediate award of $500 million. Had there been multiple winners, they would’ve shared the prize.

The NCAA men’s basketball tournament, known as “March Madness,” is among the most-watched sporting events in the U.S. The championship game last year attracted 23.4 million viewers, CBS Corp. said after the University of Louisville defeated the University of Michigan.

Trying to predict the winners of each game has become a fixation in the U.S., where colleagues often bet in office pools and compete against celebrities who post their picks online. President Barack Obama has made a public show of releasing his bracket, including in 2009 when he correctly selected the University of North Carolina to win.

Unusual Risks

As Berkshire’s chairman and chief executive officer for more than four decades, Buffett has specialized in taking on unusual risks. His Omaha, Nebraska-based company won a bet in 2010 on the World Cup after France was eliminated from the soccer tournament in South Africa. Berkshire also protected PepsiCo Inc. against the potential payout of $1 billion in a contest the soft-drink maker sponsored in 2003.

Buffett has used premiums from insurance policies to help build Berkshire over the last five decades from a textile maker into a business valued at more than $300 billion. Its operations now span the transportation, energy, retail and manufacturing industries.

Gilbert owns the National Basketball Association’s Cleveland Cavaliers. The team plays in an arena named for his company.

–With assistance from Zachary Tracer in New York.