Pre-print, Working paper: We analyze a new blue chips (large caps) stock index for France from 1854 to 1998. We detail its methodology and show that it differs profoundly from earlier indices, and that it is more consistent with the French financial and economic history. We suggest this result casts some doubt on many historical stock indices such as those gathered in Dimson, Marsh and Staunton "Triumph of the Optimists". We also provide some major results: investment in French stocks provided a positive real return during the 19 th century, but a negative one because of inflation and wars in the 20 th . Despite this century of negative real performance, stocks are still the best financial asset for the very long run but, with an equity premium lower than in the US.