I don't know about corporate cash but I know corporate debt is at all time high, and budget deficit is at all time high when not in recession and growing higher, and US would be in recession if not government deficit and all that debt needs buyers and that 5% yield is a mirage as you see it only in corporate earning reports but not in your pocket divs are lower than 2% - and that's exactly what S&P earns for me
money is so cheap that is why debt and cash are both at all time highs... no brainer to borrow at 3.x% to buy something earning 5.x% lol. 5.x% is real.. the trend is favoring buy-backs instead of divs due to the tax defer.