Pending home sales in March maintained their recent high level, but momentum slackened slightly in most of the country as dearth supply weighed on activity, according to the National Association of Realtors. Only the South saw an uptick in contract signings last month.  

The Pending Home Sales Index, www.nar.realtor/topics/pending-home-sales, a forward-looking indicator based on contract signings, declined 0.8 percent to 111.4 in March from 112.3 in February. Despite last month's decrease, the index is 0.8 percent above a year ago.

Lawrence Yun, NAR chief economist, says sparse inventory levels caused a pullback in pending sales in March, but activity was still strong enough to be the third best in the past year. "Home shoppers are coming out in droves this spring and competing with each other for the meager amount of listings in the affordable price range," he said. "In most areas, the lower the price of a home for sale, the more competition there is for it. That's the reason why first-time buyers have yet to make up a larger share of the market this year, despite there being more sales overall."

Pointing to revealing data from the March Realtors Confidence Index, Yun worries that the painfully low supply levels this spring could heighten price growth – at 6.8 percent last month – even more in the months ahead. Homes in March came off the market at a near-record pace, and indicating an increase in the likelihood of listings receiving multiple offers, 42 percent of homes sold at or above list price (the second highest amount since NAR began tracking in December 2012).

"Sellers are in the driver's seat this spring as the intense competition for the few homes for sale is forcing many buyers to be aggressive in their offers," said Yun. "Buyers are showing resiliency given the challenging conditions. However, at some point – and the sooner the better – price growth must ease to a healthier rate. Otherwise sales could slow if affordability conditions worsen."

Yun forecasts for existing-home sales to be around 5.64 million this year, an increase of 3.5 percent from 2016 (5.45 million). The national median existing-home price this year is expected to increase around 5 percent. In 2016, existing sales increased 3.8 percent and prices rose 5.1 percent.

The PHSI in the Northeast decreased 2.9 percent to 99.1 in March, but is still 1.8 percent above a year ago. In the Midwest the index declined 1.2 percent to 109.6 in March, and is now 2.4 percent lower than March 2016.

Pending home sales in the South rose 1.2 percent to an index of 129.4 in March and are now 3.9 percent above last March. The index in the West fell 2.9 percent in March to 94.5, and is now 2.7 percent below a year ago.