All-cash home sales skyrocketed during the summer of 2013, with their share of total sales growing by close to a third from June to August amid sustained appetite from investors, a recent spike in interest rates and tight inventory.

Cash purchases’ share of total sales leaped to 45 percent in August from 39 percent in July, according to a report release by RealtyTrac today. The rise came on the heels of a similarly abrupt month over month jump in cash purchases’ marketshare in July, when it rose to a revised 39 percent from a revised 34 percent in June, according to RealtyTrac data.

Taken together, the statistics indicate that cash purchases’ total share of home sales shot up 32 percent in just two months, July and August. Cash sales’ total share of sales in August (45 percent) was up a whopping 50 percent  from a year before, when cash sales’ share of total sales stood at 39 percent, RealtyTrac said.

What could possibly have driven such a drastic strengthening of cash sales’ hold on the market?

Daren Blomquist, vice president of RealtyTrac, breaks it down for us:

The jump in the cash sales share of the market appears to be closely tied to the recent rise in interest rates. From April to August there has been a 41 percent increase in the percentage of cash sales, and during that same time period there has been a 29 percent increase in the average 30-year fixed rate mortgage.

In addition institutional investors are an increasing share of the market, up from 9 percent in July to 10 percent in June. And we also are seeing a sharp rise in purchases at the foreclosure auction from a year ago, and these are by definition all-cash purchases.

Indeed, some housing experts attribute the growing proportion of cash sales to a rapid rise in interest rates spurred by statements from the Fed that it might begin to wind down its bond-buying program. Rates on 30-year fixed-rate mortgages began climbing in May, after hovering around record lows, thanks largely to the Fed’s stimulus program.

The jump in rates may have chipped away at demand from buyers who require mortgages, clearing the way for all-cash buyers to seize a larger share of home purchase.

Sustained demand from investors, 10 percent of whom RealtyTrac said were institutional, has swelled the ranks of these all-cash buyers, pumping a steady, strong flow of cash offers into the market.

Though there are signs that home supply is beginning to pick up, a still-sharp inventory shortage may also be helping along cash sales. When sellers receive several offers, which is common when there is scarce supply, they often opt for all-cash offers since such deals are easier to close.

Other recent data have also pointed to cash sales’ strong grip on the market. A Goldman Sachs Group report found that cash sales accounted for slightly more than 55 percent of total sales in July, up from just above 50 percent a year before, while the National Association of Realtors reported that their share of the market had grown from 27 percent to 31 percent during the same period.

Editor’s note: This story has been updated to reflect revised RealtyTrac June and July data on cash sales.