I spent the first six months of the year hearing real estate agents complain there just wasn't enough for sale to satisfy prospective buyers.

The supply shortage - that is, a shortage of houses that buyers wanted, houses that were up to date and properly priced - lasted well past the spring selling season ending June 30.

And it was widespread. For "Town by Town" in the Sunday Business section, I visited 26 municipalities and neighborhoods in eight counties, and of the 75 real estate agents and builders I interviewed, all but two started the conversations lamenting a shortage of listings.

The shortage created a seller's market for the first time since the housing bubble burst in 2007's third quarter.

Veteran agent Gary Segal, who sells in eastern Montgomery County from Keller Williams' Blue Bell office, said Realtors define a seller's market as one with less than six months' inventory and an absorption rate of 20 percent and above.

To calculate the absorption rate, you look at how many homes sold in a given month and divide that by the total number of homes for sale at the end of the month.

So if 15 houses sold in a month and 30 houses were listed for sale on the last day of that month, the absorption rate is 50 percent - meaning it's a seller's market.

But after the usual summer sales lull ended at Labor Day, Segal and other agents said, folks began listing their houses at a pace Realtors had been hoping for back in the spring.

Unfortunately, there were fewer prospective buyers in the fall market than there had been four months earlier, so "almost overnight," Segal said, "the seller's market became a buyer's market again."

The dynamic has changed just about everywhere, said Martin Millner, an agent with Coldwell Banker Hearthside in Yardley.

"There isn't tremendous buyer demand, and yet more houses are going on the market," he said.

Millner lives in Yardley Hunt in Lower Makefield, a community of 600 single-family homes mostly built back in the early 1980s by Toll Bros. This fall, 12 houses came on the market at Yardley Hunt, more at one time than Millner ever recalls seeing,

The high-end market dynamic is changing as well, Millner said. He repeated an observation by a friend of his who sells more expensive houses that "it is the worst he's seen in 35 years."

As I like to emphasize, real estate is local down to the neighborhood and even the block. But I'm hearing the word oversupply just about everywhere in the region now.

Where have all the buyers gone?

Alex Villacorta, vice president of research at Clear Capital, observed that September was the 11th month of moderating gains, with home-price levels back in line with long-run averages.

"With less fuel stoking investors' fire, and the consumer yet to feel confident in the market," he said, "we expect at best either a return to prebubble norms or a departure into negative territory."

If improvements in the job market continue to support a rise in consumer confidence, Villacorta said, it's likely that buyers who intend to own and occupy will be encouraged to pick up the slack in housing demand once held steady by investors.

If you know you'll have a job Monday, you'll sign a sales agreement Sunday, consultant Gary Schaal once told me.

Thus, it's all about consumer confidence, plain and simple.

"While [consumer] sentiment data is improving as of late, we've yet to see sentiment reach prerecession levels," Villacorta said. And, he noted, the next few months will tell the story.

215-854-2472 @alheavens