Yahoo may have hung out a "for sale" sign, but it hasn't done much to improve its curb appeal.On Tuesday, the company posted a first quarter loss on a sharp drop in net revenue, a figure that subtracts ad commissions from total turnover. Yahoo's net revenue fell 18 percent from year-earlier period to $859 million. It's the largest decline in Yahoo's quarterly net revenue since the company hired Marissa Mayer as its CEO nearly four years ago. The company expects an even bigger net revenue drop of 20 percent in the quarter ending in June. Yahoo lost $99 million during the first quarter, compared to a $21 million profit last year.Verizon Communications has publicly said it's interested in buying Yahoo. It snapped up another fallen Internet star, AOL Inc., for $4.4 billion last year. The Daily Mail in London also has said it was mulling a bid. Analysts believe private equity firms that specialize in buying and turning around troubled companies are interested.