(FORTUNE Magazine) – Unloading valuable assets is common at IBM these days. Nearly half the work force has been dismissed, close to $2 billion in real estate was sold off in 1994, and now the cream of its vast art collection goes under the hammer this month at Sotheby's in New York City.

Many of the 300 paintings, drawings, and prints, expected to bring at least $25 million, date to founder Thomas Watson Sr. A passionate collector and unsalaried art ambassador for Franklin D. Roosevelt, Watson began a decade-long buying spree in 1937.

His taste was eclectic. One group of 19th- and early-20th-century traditional American paintings is touted by Sotheby's as the "finest ever to appear on the auction market." Among them are works by George Bellows, Frank Benson, and Winslow Homer, each pegged to go for $1 million to $2 million.

There's also an arresting group by Latin American artists, including Mexico's 20th-century master Diego Rivera, and his colorful wife, Frida Kahlo, whose rare self-portraits are hot. (Madonna is a collector.) Rivera's Baile en Tehuantepec is expected to fetch $3 million or $4 million, and Kahlo's powerful Self-Portrait With Monkey and Parrot may pull in $3 million.

In the past, big corporations rarely parted with their art collections, but in the grittier 1990s it is no longer unusual. USX auctioned off 58 contemporary pieces in 1990 for $3.5 million, and Alcoa's European contemporary collection goes on the block this summer.

- Faye Rice