The savings rate of wealthier Americans has skyrocketed since the financial crisis, creating a huge cash hoard with possible implications for the overall economy.

The savings rate of the wealthiest 1 percent was 37 percent in the second quarter this year, more that three times their 2007 savings rate, reveals research from American Express Publishing and Harrison Group, CNBC reports. It's also up from 34 percent in the second quarter of 2012.

According to a study from Bank of America, 56 percent of millionaires have a "substantial" amount of cash, CNBC notes. Only 16 percent said they plan on investing the cash in the next couple months, and 40 percent plan to invest it within the next two years.

Editor’s Note: 399% Stock Market Rally Predicted (Buy These 4 Stocks Now)

Their substantial saving rates may have large implications for the overall economy. Cash held by the wealthy is filling bank savings accounts and money market accounts, yet the stock market has reached record levels despite the considerable cash hordes on the sidelines.

Many wealthy participants in a survey by Spectrum Group said they wished they had done things differently in the years before the financial crisis, CNBC states. The top responses were they wished they had saved more, done more research on their finances or not taken on as much debt.

Overall, Americans' personal savings rate was 4.1 percent for 2012. A Commerce Department accounting change revised that rate to 5.6 percent, according to The Washington Post. The savings rate was revised from 3.5 percent to 5 percent for 2002, and from 1.5 to 2.6 percent for 2005.

The Bureau of Economic Analysis started to count expected pension payments in Americans' savings, prompting an increase in the savings rate. The extra savings is only on paper. As The Post notes, some companies and local governments, such as Detroit, may not have the money to fund those pensions.

Like other Americans, the wealthy became fearful of the risk of investing in stocks after the financial crisis. Yet the rising stock market has benefited wealthier Americans more than other income groups since they hold a great portion their assets in stocks, according to Pew Research Center.

For instance, average net worth per household rose 14 percent overall from 2009 to 2011, Pew data show. However, average net worth excluding home equity rose 31 percent, from $195,650 in 2009 to $255,843 in 2011.

Not counting home equity, much of the nation's net worth is in financial assets, and the nation's households with at least $500,000 of net worth were more likely to own financial assets, particularly the financial assets that have increased significantly in value.

Editor’s Note: 399% Stock Market Rally Predicted (Buy These 4 Stocks Now)