Five years ago, Karl Fowler was a trader in Goldman Sachs’ London office, specializ­ing in tax-arbitrage derivatives and equities swaps. Then his career took an even more esoteric turn—into the business of making giant books. Last year, he published his first so-called opus: a 20-by-20-inch, 97-pound doorstop about Manchester United, the English soccer team. Now, four titles later, he’s trying to securitize part of his book business by selling $50 million in bonds backed by the future value of the tomes, which are published in limited quantities and sell for $4,000 to $100,000 a copy.

This wasn’t Fowler’s plan when he left Goldman back in 2002 to start his own financial-services firm on Guernsey, the tax-friendly island off the coast of France. But after building up a client list heavy with sports figures, he hit on the idea of publishing a book for Manchester United’s rabid fans. Although Fowler wasn’t the first to create such enormous volumes—the German publisher Taschen released Helmut Newton’s 66-pound Sumo in 2000 and GOAT: Greatest of All Time, a 75-pound book about Muhammad Ali, in 2004—his Kraken Opus is the first imprint devoted to the niche. Out this month is a book on Formula One; in the works are titles on Disney, Playboy, the Rolling Stones, and even the Vatican.

Collectors of Fowler’s books are almost as diverse as their subject matter. According to Fowler, George Soros, Mike Tyson, and hedge fund manager Stanley Druckenmiller each paid $40,000 for Super Bowl books inscribed with the signatures of every living Super Bowl M.V.P.; advertising veteran Charles Saatchi coughed up the same amount for an M.V.P. edition of the Manchester United book. (The standard, unsigned versions of these volumes typically cost $4,000 each.) The average print run is 3,000 copies, and sales are restricted to create scarcity.

The object, of course, is to foster a market in which the books can appreciate in value. “People are increasingly interested in investments that meet their criteria from a return point of view but also have an aesthetic bent,” says Fowler. He says the bonds, which are unrated, are fully subscribed by investors, who paid $250,000 to $5 million for their stakes. Each batch of three-, five-, and seven-year notes, which offer a 7.5 percent return, can be exchanged for Kraken books or cash.

It’s an open question whether the books will perform as an investment, especially in an environment where bond buyers are fleeing to safer, higher-quality securities. “In recent years, the credit performance of these types of esoteric, asset-backed securities has been good, with very few problems,” says Jay Eisbruck, a managing director at Moody’s Asset Finance Group in New York. “But because less historical data tends to be available for predicting their future performance, you have to factor in a lot more variability on the risk.”