Russian Billionaire Moves a Step Closer to Buying the Nets

The Russian billionaire Mikhail D. Prokhorov moved closer to taking control of the Nets on Tuesday night when he signed formal contracts to buy a controlling stake in the team and to invest in its new home, a billion-dollar arena planned as part of a development in Brooklyn.Under the terms of the deal, Prokhorov would become the principal owner of the Nets and the first overseas owner of an N.B.A. team.