The US economy grew less than forecast in the second quarter, after almost coming to a halt at the beginning of the year. Gross domestic product rose 1.3 per cent annually, following a 0.4 per cent gain in the previous quarter, which was less than earlier estimated, Commerce department figures showed today. The median forecast of economists surveyed by Bloomberg News estimated a 1.8 per cent rise. Household purchases, about 70 per cent of the economy, rose 0.1 per cent. Slower job and income gains raise the risk that a pick-up in purchases during the remainder of 2011 would fail to materialise.