Updated with premarket pricesWALTHAM, Mass. ( TheStreet) -- Novell ( NOVL) said its board will review a buyout offer valued at about $2 billion from private-equity firm Elliott Associates. In a statement, Novell acknowledged receipt of the unsolicited proposal from Elliott for $5.75 a share in cash. Novell shares closed Tuesday at $4.75, but soared 25.9%, or $1.23, to $5.98 in after-hours trading. The Elliott offer was disclosed just after the market closed Tuesday. In premarket trades Wednesday, the stock rose to $6.11. Elliott already owns about 8.5% of enterprise software maker Novell, meaning its offer is for the remainder. Elliott portfolio manager Jesse Cohn, in a letter to Novell's board, said the private-equity firm's offer implies an enterprise value, net cash, of $1 billion. Elliott said its offer price represents a premium of 49% over Novell's current enterprise value and 77% over Novell's 90-day volume-weighted average enterprise value. "By any measure, we believe our proposal represents a compelling opportunity that your stockholders will find extremely attractive," the letter said. Elliott began buying Novell shares around Jan. 4. It said its offer is a premium of 115% over Novell's enterprise value on that date. -- Reported by Joseph Woelfel in New York. Follow TheStreet.com on Twitter and become a fan on Facebook.