IT has taken 88 months, or nearly three-quarters of the decade, but the American stock market is finally back to where it ended the last decade.

At least that is true if one measures stock performance in the traditional way, using dollars. As the chart accompanying this column indicates, the Standard & Poor’s index of 500 stocks ended April a full 1.1 percent above its level of Dec. 31, 1999.

Unfortunately for those who owned American stocks during that period, the dollar itself has not been a star performer. As a store of value, the buck is having a bad decade.

The charts show how the S.& P. has performed against some other currencies, and against some alternative investments.