Extending a run of improving housing data, the homebuilders' housing market index shot up 5 points to 14 in April, the biggest gain in six years and the best level since October. All components showed improvement especially single-family purchases six months out. Demand for homes is getting a boost from low prices, low mortgage rates, and an $8,000 first-time buyer credit. The report said April's jump suggests that the housing depression is at or near the bottom. There was no significant reaction, at least initially, to the report. Housing starts will be released tomorrow morning.