WASHINGTON (MarketWatch) - U.S. economic growth accelerated to an annual rate of 4.1% in the second quarter, compared with a revised 2.2% in the first quarter, the Commerce Department said Friday. This is the fastest rate of growth in almost four years. The second quarter gain was close to the 4.2% rate economists surveyed by MarketWatch had forecast. The acceleration of real gross domestic product in the second quarter reflected a jump in consumer and government spending. The trade sector boosted GDP but this was offset by a downturn in inventory investment. Real final sales for domestic purchasers, which excludes trade and inventories, rose 3.9% in the second quarter after a 1.9% gain in the prior quarter.