Wall Street has a 1 percent problem at least as big as Main Street's.

Americans have been talking about the concentration of wealth among the wealthiest Americans for years, but it turns out corporate America suffers from a similar problem. According to a new study by Standard & Poor's Rating Service, U.S. corporations hold a record $1.82 trillion in cash. But the top 1 percent holds 48 percent of it.

The rest of corporate America has been piling on the debt, facilitated by investors seeking higher returns in a low interest rate environment. That could spell bad news for the U.S. economy if those companies issuing debt can't pay it off, kind of like the way sub-prime mortgage holders couldn't pay their debts during the Great Recession.

"The cash growth looks strong overall, but without the top 1 percent, total cash balances would have declined in 2014. And should the credit markets tighten and interest rates rise, liquidity risk will become more pronounced for the remaining 99 percent," wrote Standard & Poor's credit analyst Andrew Chang.

Rather than taking out mortgages, corporations issue bonds that they promise to pay off over time with interest. The interest rates on bonds, like mortgage interest rates, are calculated based on the Federal Reserve's interest rates.

The Fed has kept interest rates near zero for the last seven years to stimulate the economy. The bottom 99 percent of corporations have issued bonds to take advantage of the low rates and investors have bought the bonds seeking a higher return on their cash. But unlike U.S. government bonds, which are guaranteed, corporate bonds can be extremely risky.

According to S&P, corporate debt grew by $650 billion in 2014, six times faster than the amount of cash saved by corporations. Part of the reason is that cash doesn't show up on balance sheets when global corporations decide not to repatriate foreign profits so they can avoid U.S. taxes.

But in other cases, companies are putting themselves deeper in debt.

High-technology and health care firms make up the top 1 percent. Among the 99 percent are oil and gas exploration and production firms hit hard recently by a drop in oil prices. E&Ps have issued $34 billion in new bonds this year, betting that oil prices will rise again soon.

If the Fed raises interest rates later this year, investors will be less likely to buy corporate bonds and many analysts think there could be a bubble in the corporate bond market. The S&P study should be considered a red flag.