CHICAGO — The Tribune Co. has reached a written agreement to sell the Chicago Cubs, Wrigley Field and other assets to the family of TD Ameritrade founder Joe Ricketts for about $900 million, a person close to the negotiations said Monday.

The agreement was reached over the weekend and a document outlining the deal — called a term sheet — was sent to Major League Baseball for review, according to the person, who spoke on condition of anonymity because the agreement had not been announced.

The term sheet is not a final agreement, according to the person, who added that it contains details on how the Ricketts family will finance the deal. The deal also would give the Ricketts family a 25 percent interest in a regional cable television sports network.

The team has been on the market since 2007, when real estate mogul Sam Zell announced his $8.2 billion purchase of Tribune Co. The financially troubled media giant filed for bankruptcy last December but the Cubs were not included in the filing.

Tribune Co. announced in January that the Ricketts family bid had been selected over two others for the team.

Cubs fans have greeted the news enthusiastically, in part because the Ricketts family in general, and the family point man in the bid in particular, are viewed as loyal Cubs fans.