Vornado Buys 4.3 Pct. Stake, Shares Soar  NEW YORK (Reuters) - Shares of Sears, Roebuck and Co. were  up about 20 percent on Friday after real estate company Vornado  Realty Trust said it raised its stake in the retailer, a step  that could mean Sears plans to convert some of its real estate  assets into cash.