Sears Holdings Corp.'s stock today tumbled nearly 9 percent in midday trading to a 52-week low on news that the beleaguered retailer has taken a $400 million loan from its CEO, hedge fund billionaire Edward Lampert. Analysts say the loan, announced yesterday, suggests that Sears is having a tough time finding decent prices for the business segments it's trying to sell to raise cash. Others wonder if Mr. Lampert is getting a sweet deal on the loan's terms. Sears, which has closed more than 300 stores since 2010, is divesting other properties and assets.