The Tribune Co. has reached an agreement to sell the Cubs, Wrigley Field and other assets to the family of Joe Ricketts for about $900 million. The agreement was reached over the weekend and a term sheet?was sent to Major League Baseball for review, according to a source. "We continue an active dialogue with the Ricketts family with an eye toward reaching a definitive agreement," Tribune Co. spokesman Gary Weitman said in an e-mail. "We don't intend to comment on the specifics of any potential transaction."