(Reuters) - Wall Street tumbled for a second straight day on Tuesday as a collapse in U.S. oil prices and glum forecasts by companies foreshadowed the worst economic slump since the Great Depression. All 11 S&P 500 sector indexes fell 1.5% or more, with energy . SPNY sliding for the seventh time in eight sessions a day after the WTI contract CLc1 crashed below zero as oil traders ran out of storage for May deliveries. With the collapse spilling into June futures contracts, equity investors became wary of the extent of the economic damage from sweeping lockdown measures that have halted business activity and sparked millions of layoffs.