Piles of cash built up since the financial crisis have left big US companies sitting pretty as financial markets gyrate, but their reluctance to invest is holding back US growth. The result is that while corporate America is looking good amid all the instability, the country is still suffering a 9.1 percent unemployment rate two years after the \"Great Recession\" officially ended. Even as they build up rainy day money, nervousness over weakness not only in the US but world economy is keeping the country\'s corporate leaders cautious. \"Companies have a lot of cash on the balance sheet,\" Mitchell Petersen, a finance professor at Northwestern University in Chicago, told AFP. But they \"are concerned about being able to get capital if they need it,\" he said. Memories of easy credit that evaporated in the financial meltdown from the Lehman Brothers bankruptcy in September 2008 are still vivid, he explained. Financial directors prefer to hold cash on their balance sheets rather than risk finding themselves short of capital if credit lines were to suddenly dry up again. Excluding the financial sector, companies on the Standard & Poor\'s 500-stock index are holding a cash pile of $1.15 trillion, according to S&P\'s research unit Capital IQ. US companies ended 2010 with cash holdings 11.2 percent higher than end-2009, and that was despite spending \"far more\" on capital expenditures, shareholder distributions and mergers and acquisitions, rating agency Moody\'s said in a recent report. The industries hoarding the most were technology ($264 billion), pharmaceuticals ($141 billion) and energy and consumer products (each holding more than $100 billion). Apple, Microsoft, Cisco, Pfizer and Google had the deepest cash cushions. And although interest rates are at historic lows, the ratio between corporate debt and cash is at its lowest since 2006, as companies use their added funds to retire old debt, Moody\'s said. The big US companies could choose to invest, to launch share buy-backs, or raise dividends paid to their shareholders. But many are taking a wait-and-see approach \"because the expected future is kind of gloomy and... very uncertain,\" Petersen said. With the sovereign debt crisis rattling Europe and the United States struggling to reduce its rising debt and deficits, the huge uncertainty makes investment riskier than a few years ago, he said. A chief executive or chief financial officer is going to want to wait \"three months, six months, one year\" before building a new factory, for example, he said. \"Why would they want to invest?\" For the same reasons, companies are delaying expanding operations and workforces. \"With the economy still teetering, most companies are not willing to make a commitment to job creation,\" John Challenger, at outplacement firm Challenger, Gray & Christmas, told AFP. \"They don\'t want to hire 1,000 workers next month only to lay them off six months later because demand did not materialize.\" But that is not helping those who expect business to power up the economy and generate more jobs for the 14 million unemployed. Sinking equity prices and wider spreads \"tell businesses that this is not the time to expand operations and that it might be best to put off replacing worn-down and obsolete capital equipment,\" said Moody\'s economist John Lonski in a research note Thursday. \"Moreover, sharply lower share prices might compel businesses to conserve cash by trimming payrolls,\" he added. A case in point: disinfectants maker Ecolab, which announced in late July a $5.4 billion deal to buy rival Nalco, said it was \"continuing to invest in our sales force and innovations.\" But Ecolab spokeswoman Kari Bjorhus stressed to AFP that the company was \"continuing to manage our expenses very prudently.\"