Retail disasters come in different forms. Walk into a J.C. Penney store these days, and you're likely to see an appealing work in progress, with lovely ­signage, spiffy layouts and popular brand-name merchandise beautifully displayed. It shouts, "I'm soooo trendy." Walk into a Sears or a Kmart, and you're likely to see the department store equivalent of tumbleweeds: scuffed floors and indifferent merchandise plopped sloppily onto tables and shelves amid a dingy atmosphere. It wheezes, "Time has passed me by." But these retailers have several things in common. One is a woeful lack of customers. A second, which you don't see but helps account for the precarious state in which the chains find themselves: They're all heavily influenced by Wall Street guys who convinced themselves - and, for a while, a whole lot of others - that they understand what Main Street wants. And they got it wrong. We're dealing here with two big investors who are polar opposites in personality and approach. There's the flashy Bill Ackman of Pershing Square Capital Management. Two years ago, he used his hefty stake in Penney to muscle its board into hiring Ron Johnson, creator of the mega-successful chain of Apple retail stores, who in turn has embarked on a radical, so far disastrous strategy. And there's the reclusive Eddie Lampert of ESL Investments. This year, he appointed himself acting chief executive of Sears Holdings, which owns Sears and Kmart. But the two Wall Streeters, so different in many ways, are alike in thinking that they have the talent and the chops to give a troubled national retail chain what it needs to succeed. So far, at least, they haven't come close. Ackman and Lampert became billionaires by being brilliant investors, and both got into retailing by amassing big stakes in companies they thought were selling for way less than their assets were worth. Under Ackman's influence, J.C. Penney is spending heavily to upgrade its stores from dowdy to delightful; Lampert is slowly milking a dwindling asset and revenue base at Sears. Both companies find themselves in serious trouble. Perils of Penney By now the Perils of Penney has become a familiar tale. After soaring on the appointment of Johnson as chief executive, Penney stock has collapsed in recent weeks. It has fallen 30 percent in less than a month, after a disastrous fourth-­quarter earnings report. It's down 60 percent since Johnson brazenly claimed in January 2012 that he would transform the fading chain into "America's favorite store." Ackman's ally at JCP (as it now wants to be called), Steve Roth of Vornado Realty Trust, abruptly sold 40 percent of the company's stake in March; a Macy's lawsuit over plans to open Martha Stewart "stores" inside JCP locations drags on, temporarily leaving a gaping hole in hundreds of Penneys; and on March 14, lender CIT reportedly signaled its skepticism about the company's finances by boosting the cost for vendors to borrow against payments that Penney owes them. Johnson swept into Penney in November 2011 with the celebratory air of a revolutionary rolling into a vanquished capital. A few months later he hosted a gala relaunch of the brand, a Penney-palooza modeled after the Apple fests held by his former boss Steve Jobs. Even Jobs might have considered this one excessive.