So-called “shadow” inventory – homes facing foreclosure or owned by banks and other lenders after foreclosures but not on the market — reached 2.1 million units in August,

or eight months worth of supply, up from 1.9 million, or a five-months’ supply, from one year earlier, according to figures compiled by financial information company CoreLogic.

With visible inventory remaining flat at 4.2 million units, the change in shadow inventory increased the total supply of unsold inventory by 3 percent.

The total visible and shadow inventory was 6.3 million units in August, up from 6.1 million a year ago. That adds up to 23 months worth of unsold homes at the current selling pace, up from 17 months a year ago.

Although it can vary and it depends on the market and real estate cycle, typically a reading of six to seven months is considered normal so the current total months’ supply is roughly three times the normal rate.

In its analysis, CoreLogic also found that the highest levels of distressed months’ supply, which is the ratio of the number of properties that are 90+ days or more delinquent to the number of sales, are in Florida, Michigan, and California. Although Phoenix and Las Vegas have high months’ supply of total housing inventory, they are not among the markets with the highest distressed months’ supply because of the increased number of distressed sales that have been occurring in those markets. The markets with the lowest distressed supply are all in Texas, which largely bypassed the housing boom and subsequent bust.

“The weak demand for housing is significantly increasing the risk of further price declines in the housing market,” says Mark Fleming, chief economist for CoreLogic. “This is being exacerbated by a significant and growing shadow inventory that is likely to persist for some time due to the highly extended time-to-liquidation that servicers are currently experiencing.”