The peculiar, plucky story of Investor’s Business Daily.

In August 2007, Rupert Murdoch's News Corp. conquered the Bancroft family to win control of the Wall Street Journal. In the months since the $5 billion deal was completed, the media commentariat has chattered over how Murdoch's imperial ambitions would remake the financial press. At the time of the acquisition, the Journal faced challenges from an acute downturn in business-and-technology advertising, as well as a competitive business-media landscape crowded by the Financial Times and an invigorated New York Times business section.

Through all that noise, you'd hardly know that there was a third national business paper that has been published since 1984, counts more than 150,000 subscribers—almost identical to the FT's U.S. circulation—and won a Pulitzer Prize last year for editorial cartoons. Investor's Business Daily might be the biggest newspaper no one has ever heard of. It is also the strangest mainstream newspaper in America.

The five-day-a-week paper, which is based in Los Angeles, is known to most people as a staple of late-night infomercials or giveaways in West Coast hotel lobbies. My trio of local newsstands in Brooklyn Heights all shrugged blankly when I inquired about purchasing a copy of IBD on a recent morning. Mind you, I don't live in some hinterland: Wall Street is just one subway stop away.

When I called publishing and investing experts to ask about IBD, they seemed equally clueless. "I don't know much about it. I don't read it," renowned newspaper analyst John Morton said. Peter Tanous, president of the $1.6 billion Lynx Investment Advisory, jokingly likened IBD's chances against the Journal to Microsoft's ill-fated attempts to compete with the iPod. "Do you know anyone who actually owns a Zune?" he asked.

So, just what is IBD, and who reads it? IBD was founded in April 1984 by investor and entrepreneur William O'Neil, who wanted to publish a paper that espoused his personal stock-picking philosophy of momentum investing. Unlike other strategies that promote buying on the dips, O'Neil believes stocks that are rising continue to rise, and you need to buy into an ascending market.

After studying reams of historical data, O'Neil developed a stock-picking system that he dubbed "CAN SLIM." The acronym summed up his theory that investors could make a profit if they buy shares in companies that boasted a high quarterly earnings growth of 25 percent or more for the previous two quarters, demonstrated annual earnings growth of 25 percent for the previous three to five years, were new companies with recent IPOs, showed large increases in trading volume that indicated high demand for the stock, had institutional investors buying shares, and traded in a bull market that was trending upward as a whole. O'Neil also believed strongly in knowing when to cut losses: He admonished investors to sell any positions that had declined more than 7 percent in value, no matter what. As O'Neil tells it, if his investors had sold their shares in 2000, when he told them to, they would have avoided the pain of the Nasdaq crash.