Much of the estimated $1.7 trillion in cash American companies say they have indefinitely invested overseas is actually sitting at home, according to a Wall Street Journal analysis today. Some companies, including Internet giant Google Inc., software maker Microsoft Corp. and data-storage specialist EMC Corp., keep more than three-quarters of the cash owned by their foreign subsidiaries at U.S. banks, held in U.S. dollars or parked in U.S. government and corporate securities. In the eyes of the law, the Internal Revenue Service and company executives, however, this money is overseas. As long as it doesn't flow back to the U.S. parent company, the U.S. does not tax it. And as long as it sits in U.S. bank accounts or in U.S. Treasurys, it is safer than if it were plowed into potentially risky foreign investments.