WASHINGTON — Home resales in September clocked the largest monthly increase in 26 years as buyers scrambled to complete their purchases before a tax credit for first-time owners expires.

Sales jumped 9.4 percent to a seasonally adjusted annual rate of 5.57 million last month, from a downwardly revised pace of 5.1 million in August, the National Association of Realtors said today.

That pace was the strongest in two years and beat Wall Street forecasts. Sales had been expected to rise to an annual rate of 5.35 million, according to economists surveyed by Thomson Reuters.

"There's a mini-boom going on in the housing market," said Thomas Popik, who conducts a monthly survey of real estate agents for Campbell Communications, a research firm.

Nationwide sales are up nearly 24 percent from their bottom in January, but are still down 23 percent from four years ago.

Prices, however, continued to be dragged down by foreclosures and short sales, where the mortgage exceeds the sales price. The median price last month was $174,900, down almost 9 percent from $191,200 a year earlier, and slightly lower than August's median of $177,300.