The inventory crunch caused the time a property lists until it goes into contract to reach a new low in June, at 36 days, according to Redfin.

This is down one day from the previous low, set in May at 37 days.

"This market is unlike any we've ever seen before," Redfin Chief Economist Nela Richardson said in a press release.

"Month after month, new records are set for the pace at which homes are going under contract. Demand continues to swell while supply troughs. For buyers competing in this market, it's survival of the fittest. The strongest offers that are most likely to close quickly and smoothly rise to the top of the pile."

The most competitive markets are Denver, Portland, Ore., and Seattle, where the median time from listing to contract was just seven days.

The Bay Area had the nation's most competitive markets, Redfin said. Almost three-quarters of the homes sold in San Jose, Calif., 73.7%, entered contract at above the list price. In San Francisco, this was true for 70.6% of sales, while 69.8% of sales in Oakland were for over the list price.

Nationwide, 26.6% of sales were for above the list price, while the average sales-to-list price ratio was 95.5% in June.

There is a just a 2.5-month supply of homes for sale, down 10.7% from May, and the lowest supply seen since 2010, when the company started tracking this data. A six-month supply is considered a balanced market between buyers and sellers, Redfin said.

Home prices rose 7.3% to a median of $298,000, the highest Redfin has seen in its seven years of tracking data.

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