Investment and vacation home sales surged in 2011 as more investors jumped into the market with cash in hand to acquire distressed and affordable properties, the National Association of Realtors said.

The combined share of investment and vacation home sales last year reached its highest level since 2005, NAR said. The association's study shows investment-home sales growing 64.5% to 1.23 million in 2011, compared to 749,000 in 2010.

Vacation-home sales also jumped 7% to 502,000 last year, compared to 469,000 in 2010. In all, vacation purchases represented 11% of all transactions in 2011, compared to 10% in 2010.

Investment sales made up 27% of 2011 transactions, compared to 17% in 2010. Lawrence Yun, chief economist for NAR, said investors have been popping up in the market with cash in hand to acquire homes as prices sink to affordable levels along with low interest rates. 

"During the past year, investors have been swooping into the market to take advantage of bargain home prices," he said. "Rising rental income easily beat cash sitting in banks as an added inducement. In addition, 41% of investment buyers purchased more than one property."

NAR notes that 49% of investment buyers paid cash last year, while 42% of vacation-homebuyers did the same.

About half of the investment homes acquired were distressed homes, compared to 39% of vacation homes.