Apple's $147 billion cash pile accounts for 10 percent of overall cash held by U.S. corporates, according to Moody's Investors Service, up from 9.5 percent at the end of 2012.
U.S. corporates held a total of $1.48 trillion in cash as of 30 June 2013, up 2 percent from the previous record $1.45 trillion at the end of 2012. The survey covers 1,067 non-financial companies based in the U.S. and rated by Moody's.
(Read more: Companies spending cash on investors, not workers)
Yet Apple's cash hoard is almost double that of Microsoft, for example, which has $77 billion.
Apple has been active in returning cash to shareholders over the past 18 months. In April, the company pledged to spend $60 billion in buying back its stock by the end of 2015. By June, it had re-purchased $16 billion worth of its stock.
However, investors including billionaire activist investor Carl Icahn believe the company should do more. Icahn revealed on Tuesday that he had dinner with Apple CEO Tim Cook and urged him to increase its stock buyback program.
Icahn said in August that if Apple would issue a larger share buyback, the stock could be worth as much as $700 a share. Apple shares traded at $487.96 on Tuesday.
(Read more: Apple shareholders cross fingers for bigger buyback)
Cash not confined to techs
After the technology sector, the healthcare and pharmaceutical industry is the next most cash-flush sector, according to Moodys. Pfizer, for example, is sitting on a $50 billion cash pile.
— By CNBC's Ansuya Harjani; Follow her on Twitter @Ansuya_H