New York: There’s more cash available to buy shares than at any time in almost two decades, a sign to some of the most successful investors that equities will rebound after the worst year for US stocks since the Great Depression.

The $8.85 trillion held in cash, bank deposits and money-market funds is equal to 74% of the market value of US firms, the highest ratio since 1990, according to Federal Reserve data compiled by Leuthold Group and Bloomberg.

Turnaround trigger: Traders at the New York Stock Exchange. The eight previous times that cash peaked compared with the market’s capitalization, the 500 rose an average 24% in six months / Bloomberg

“There is a store of cash out there that is able to take the market higher," said Eric Bjorgen, who helps oversee $3.4 billion at Leuthold. “The same dollar you had last year buys you twice as much S&P 500 as it did a year ago."

Leuthold Group, whose Grizzly Short Fund returned 83% in 2008 thanks to bets against equities, said in its December bulletin to investors that stocks offer one of the great buying opportunities of a lifetime.

The S&P 500 rose 16% from an 11-year low on 20 November as the government rescued New York-based Citigroup Inc., President-elect Barack Obama pledged to stimulate growth with the biggest infrastructure investment since the 1950s, and the Fed cut interest rates to as low as 0% to combat the worst financial crisis in seven decades.

The ratio of cash on hand to US market capitalization jumped 86% in the first 11 months of the year, the biggest increase since the Fed began keeping records in 1959, as the US, Europe and Japan fell into the first simultaneous recessions since World War II.

So-called money of zero maturity, the central bank’s measure of US assets available for immediate spending, is mostly held by households, according to Richard G. Anderson, an economist at the Federal Reserve Bank of St. Louis.

“What the cash pile on the sidelines represents is dry powder," said Fritz Meyer, the Denver-based senior market strategist at Invesco Aim, which manages about $358 billion. The firm’s $1.17 billion Aim Diversified Dividend Fund beat 96% of its competitors this year, and the $3.95 billion Aim Charter Fund topped 93% of similar mutual funds.

Recovery in the second half of the year will probably play out, Meyer added.

Any recovery will depend on a rebound in corporate profits and the economy after $30 trillion was wiped out from world equities this year, according to Frederic Dickson, chief market strategist at DA Davidson and Co. in Lake Oswego, Oregon.

Jobless claims reached a 26-year high this month, while economists surveyed by Bloomberg estimate household spending will fall 1% next year, the most since the aftermath of the Pearl Harbor attack. A 13% slump in the median home resale price in November from a year earlier was likely the largest since the 1930s, the National Association of Realtors said last week, damping speculation the housing market is close to a bottom.

Analysts estimate profits at S&P 500 firms will shrink 10.3% in the first three months of 2009 and 5.8% in the second quarter, bringing the stretch of earnings declines to a record eight quarters, Bloomberg data show. Gross domestic product will contract in the first half of the year before growth resumes in the third quarter, according to a Bloomberg survey of economists.

“The fuel supply is there, but people have to have a reason to use it," said Dickson, who helps oversee about $19 billion. “The Fed fired the shot out of the biggest cannon they know. Now the question is, will it hit the right mark?"

This year’s slump has left S&P 500 companies valued at an average of 12.6 times operating profit, the cheapest since at least 1998, monthly data compiled by Bloomberg show.

Cash in interest-bearing checking accounts at US banks earns less than 0.1% annually, minus inflation, according to national data compiled by Ten-year Treasury notes yield 1.03% after adjusting for the cost of living, and yields fell to the lowest level on record this month.

Seth Klarman’s Baupost Group Llc., which held 40-50% of the Boston-based hedge-fund firm’s more than $14 billion in cash, reduced its hoard by half to take advantage of falling asset prices, according to the December issue of Harvard Business School’s Alumni Bulletin.

The 51-year-old investor, who seeks shares of firms trading at discounts to measures such as assets and cash flow, was the lead editor for the sixth edition of Benjamin Graham and David L. Dodd’s Security Analysis, which laid out the principles of value investing followed by billionaire Warren Buffett.

Klarman has generated an annual compound return of 20% in the past 26 years, the Bulletin said. He declined to comment in an emailed response to Bloomberg.

Cash holdings peaked one month before equities began to recover during the two longest recessions since World War II. In July 1982, money of zero maturity as a percentage of the US stock market’s value rose to 95% before a 20-month bear market ended and the S&P 500 began a six-month, 36% advance, data compiled by Bloomberg show.

Cash on hand reached $604.5 billion in September 1974, representing a record 1.21 times US stock capitalization. That preceded a 31% gain in equities between October 1974 and March 1975, Bloomberg data show.

“If history tends to repeat itself, we’re in the exact same scenario," said Neil Hennessy, who oversees $650 million as president of Hennessy Advisors in Novato, California. “Once the money starts to come back into the market, buying is going to beget more buying. People don’t want to be left behind."

Hennessy’s Focus 30 Fund beat 96% of its peers this year.

The last time cash accounted for a larger proportion of market value was 1990. The ratio peaked at 75% in October of that year, after the savings and loan industry collapsed, Drexel Burnham Lambert Inc. was forced into bankruptcy and the US fell into a recession. The S&P 500 rallied 23% in six months and almost 30% in a year.

Robert Doll, the chief investment officer of global equities at BlackRock, has been buying stocks anticipating the S&P 500 may rise as much as 20% next year. The firm oversees $1.3 trillion. “It’s a mountain of cash," Doll, who is based in Plainsboro, New Jersey, said on Bloomberg Radio. “Somebody’s just got to find the match and light it."

Thomas R. Keene, Ken Prewitt, Joe Evangelista and Phyllis Halliday in New York and Sree Vidya Bhaktavatsalam in Boston also contributed to this story.