Warren Buffett says you could torture him, and he still wouldn't tell. The world's most famous investor, the Sage of Omaha, has chosen his successors, the duo who will take over at the helm of the Berkshire Hathaway business empire, but he's not saying who it is.

The topic will be on the minds of many of the 30,000 Berkshire Hathaway investors who are expected to make the trip to Omaha, Nebraska, for the company's shareholder meeting in May.

There has been a flurry of speculation about one name in particular, a certain Byron Trott, who has just quit as head of the Midwestern office of Goldman Sachs in Chicago.

Trott is "a rare investment banker who puts himself in his clients' shoes", Buffett has said, praise indeed from a man who is normally disdainful of "the priesthood of finance" and bankers out for a fast buck.

Trott is setting up on his own, creating a merchant bank called BDT Capital Partners, and Buffett likes him so much he is buying into the company.

The two men share a Midwestern background and sensibility, hailing from a part of the US that usually spurns the flash of the West coast or the cut-throat instincts of the East.

In Chicago, Trott, 50, is most famous as a workaholic, jetting around the 13 states in his purview and leaving voicemail messages for clients in the middle of the night.

Investment bankers are the diplomats of finance, searching for a deal that will make all the parties happy, and Trott is the quintessential middleman. He is well-connected, discreet and eminently trustworthy, and he speaks his mind.

Even his political donations look astute. While he has given most money to the Republican Party, he has attended fundraisers for politicians on both sides of the aisle and of both hues in presidential races.

His one piece of flash is a giant home on the shore of Lake Michigan, built from scratch. The 1.2 hectare parcel of land alone cost him US$11.4 million ($20.4 million).