NEW YORK — For the ultimate in liquid investments, try top-quality wine, which has outperformed one benchmark U.S. stock index for 13 years and withstood two recessions.

That's the conclusion of Philippe Masset and Jean-Philippe Weisskopf, two Switzerland-based economists who compared wine prices with the Russell 3000 Index between January 1996 and January 2009. The researchers studied more than 400,000 prices on regularly traded wines from the 13-year period, which covers two bull markets and two bear markets for stocks, to construct a general wine index and a gauge of top vintages.

"My wine cellars have probably appreciated better than any other investment I have made personally," said Drew Nieporent, owner of Corton, Nobu and Tribeca Grill in New York. The third restaurant holds a 2009 Grand Award from Wine Spectator magazine. "Great wines are scarce," he said. "You can't get them everywhere."

Demand for alternative investments such as wine and artwork has grown in recent decades as investors seek refuge from inflation, and look for asset classes in which to store wealth beyond traditional methods such as stocks, bonds and gold, according to Peter Boockvar, an equity strategist at Miller Tabak & Co. in New York.

"It's the demand for hard assets, and it's the same reason why gold and oil are rallying," Boockvar said. Gold futures are advancing for a 10th straight year, and crude trades above $80 a barrel in New York, a level never exceeded before 2007.

Masset and Weisskopf took prices from 144 auctions with a combined value of $237 million to construct the index. They used vintages from 1981 to 2005.

"Our findings show that the inclusion of wine in a portfolio and, especially, more prestigious wines, increases the portfolio's returns while reducing its risk, particularly during the financial crisis," wrote Masset, a professor at the Lausanne Hotel School, and Weisskopf, a researcher at the University of Fribourg, in their study, "Raise Your Glass: Wine Investment and the Financial Crisis."

The general wine index beat the Russell 3000 over the period, largely because it held value over the most recent market downturn — and did so with lower volatility than equities. Since mid-2008, the wine measure fell 17 percent, while the stocks gauge declined 47 percent.

The index of highest-quality wines, "first growth wines of top vintages only," in particular from 2005 onward, "hugely outperforms" the other two indexes, the authors said. The elite gauge has a more than fivefold return, while the regular wine index has more than doubled. The Russell 3000 gained about 50 percent.

The increase in prices coincided with an increase in consumption of the beverage. Americans drank a record 304 million cases in 2009 following a 3.2 percent average annual rise since 1996, according to the last year's edition of "The Global Drinks Market: Impact Databank Review & Forecast. (There are nine liters of wine in a case.) Global consumption has grown 0.6 percent a year on average to 2.65 billion cases during the same period.

The monthly Liv-ex 100 Fine Wine Index tracks the price movements of 100 of the most sought-after wines offered in the resale market. The index rose 11.7 percent during the first three months of 2010 and jumped 27.6 percent from a year earlier as of March 31, according to data compiled by Liv-ex.com.

Wine isn't an investment for the unprepared, said Peter Meltzer, auction correspondent for Wine Spectator magazine. The market is thinly traded compared with stocks. Bottles need to be handled carefully and stored properly to avoid breakage or spoiling. Collectors who aren't familiar with vintages, varietals and appellations could find themselves saddled with a product that's much less desirable than they'd expected.

Because wine doesn't generate dividends or interest like stocks or bonds often do, the only way to calculate its value is to guess how much people will be willing to pay for it in the future, making it a speculative instrument, said Glenn Tongue, a partner at T2 Partners LLC in New York.

"We get no cash from wine and we have no idea what we can sell it for down the road, so we're not going to invest in it," said Tongue, whose Tilson Focus Fund has almost doubled investors' money in the past year, beating 99 percent of peers. "It's speculation when you're buying wine or art. It's not an investment."

Top wine vintages have been the best performers since 1996 with wines costing more than $200 a bottle — and particularly collectible bottles above $400 — as much as quadrupling their value. That compares with a 170 percent increase in the price of wines selling below $100 and a 120 percent return for those between $100 and $199.

The Internet has made the market for collector's items more organized and transparent because it improves the distribution of information and lowers transaction costs, according to Jim Halperin, co-founder of Heritage Auction Galleries, the third- largest art and memorabilia auctioneer after New York-based Sotheby's and Christie's International Plc in London.

While wine has done better than assets such as stocks, real estate and gold, modern art was the most attractive investment, outperforming credit, equity and commodities between 1994 and 2008, according to data compiled by Birinyi Associates Inc.

Not all wines appreciate equally and while lesser-quality wines may increase in value, they will rarely show the same performance as choice Bordeaux like Ch[0xe2]teaux P trus, Ausone, and Cheval Blanc, or Burgundies from Domaine de la Roman e-Conti and Henri Jayer, said Meltzer of Wine Spectator.

"Collectibles have become a viable and serious tool for investment diversification," said Dallas-based Halperin. "I'm investing my own money in art and collectibles, right alongside public stocks, private equity, business loans and real estate."

Low interest rates and government stimulus measures have helped boost demand for wine, said Miller Tabak's Boockvar. The Federal Reserve cut its interest-rate benchmark to a record low near zero in December 2008 and has said it will keep it there for an "extended period." The U.S. government spent, lent or guaranteed more than $8 trillion to end the worst contraction since the Great Depression.

"In a world where interest rates are zero and money is being printed around the world, there's a demand for hard assets — whether it is wine, comic books or baseball cards — because they can protect the investor from that environment," Boockvar said.