The unsolicited offer is at a premium to the REIT’s $4.7 billion current market value. : (Bloomberg)—Westdale Real Estate Investment and Management has approached Apartment Investment & Management Co. with an all-cash takeover proposal, people familiar with the matter said. The unsolicited offer for Aimco is at a premium to the real estate investment trust’s market value of about $4.7 billion before the approach was revealed, the people said, asking not to be identified as the matter is private. The target has not yet responded to the proposal, which was made last week, the people said.