An unknown bidder is set to pay more than $3 million for a private lunch with American business magnate Warren Buffett, with proceeds of the auction going directly to a homeless charity.

The weeklong eBay charity auction, which began on June 5 and ended on June 10, aimed to raise money for Glide Foundation, a San Francisco-based charity that provides food, health care and other services to people who are poor, homeless or struggling with substance abuse.

By Friday mid-morning, the bidding reached more than $2.6 million, which is approximately $300,000 greater than the 2015 winning bid made by Beijing company Dalian Zeus Entertainment Co.

By Friday night, the winning bid reached $3,456,789 (£ 2,424,881), which matched the 2012 bid that marked the private Buffett lunch as the most expensive singular charity item ever sold on eBay.

Why Glide?

The investor, who manages the Berkshire Hathaway conglomerate, has held 17 auctions and raised more than $20 million for Glide.

The private lunch auctions started after Susan Buffett, Warren Buffett's first wife, introduced him to the charity, where she had been volunteering.

Although Susan Buffett passed away in 2004, the connection between their family and Glide has endured.

Deep Investment

Buffett has praised Glide's approach in providing meals, job training, health care, rehabilitation and housing support to the homeless and poor.

He said Glide is a bridge for thousands of people who are on the brink of despair as the charity helps them "achieve dignity and opportunity" by providing them with basic necessities.

One of Glide's co-founders, Rev. Cecil Williams, said the group was astonished by the results of this year's auction.

"This one was really one of the best we've had in my over 50 years," added Williams.

Williams said the investor's interest and involvement with the charity has attracted more attention, helping it fund its $17 million yearly budget.

Glide provides an estimated 750,000 free meals and 815,000 syringes to their beneficiaries, as well as day care and after-school programs for 450 kids every year.

A Buffet Of Questions

Buffett said he receives a wide range of questions at the private lunches, which all typically last for several hours. One limit in the conversation is asking what Buffett will be investing in next, but any other topic can be discussed.

The auction winners usually eat with Buffett at the Smith and Wollensky steak house in New York City. Incidentally, the steak house donates $10,000 to Glide every year.

When the winning bidder wants to remain anonymous, the private lunch is held somewhere else.