Buffet has held 18 similar auctions annually for Glide and has reportedly raised about $26.3 million.
Buffett is auctioning off a private lunch in the hopes of raising millions of dollars more for a charity helping the homeless in San Francisco. The auction moved online in 2003, allowing worldwide fans of Mr. Buffett to participate. That's lower than last year's winning bid of $3,456,789, which tied for the record set in 2012.
$2.7 million isn't the most money this auction has ever raised for Glide.
The successful bidder alongside seven friends will dine with Buffett at the Smith & Wollensky steak house in Manhattan. The meal has sometimes moved elsewhere for anonymous winners. He became involved with Glide after his first wife, Susan, became a volunteer, prior to her death in 2004.
The auction benefits the Glide Foundation, a San-Francisco-based homeless charity.
"Everyone that has experienced Glide comes away a believer", Buffett said in a statement last month.
This year's eBay auction began Sunday and runs through Friday at 7:30 p.m. PDT. "They have to see it to believe it, but when they see it, they do believe it".
Glide uses its $18m annual budget to provide more than 750,000 free meals, emergency shelter for 8,500 people, 2,600 HIV and Hepatitis C tests, and day care and after school programmes for almost 450 children.
Past auction winners have included hedge fund manager David Einhorn and Ted Weschler, who later joined Buffett's Berkshire Hathaway Inc.to help oversee investments.
Buffett is Berkshire's chairman, chief executive officer and biggest shareholder. The investing guru - who's amassed an estimated $76.2 billion fortune, according to Forbes - co-founded the Giving Pledge with fellow billionaire and Microsoft founder Bill Gates.
Berkshire has more than 90 businesses in the insurance, energy, industrial, railroad, retail and other sectors.