Freddie Mac isn’t afraid of shadows.

The GSE released its U.S. Economic and Housing Market Outlook for August on Wednesday, examining recent trends in home price indices and speculating on the impact of shadow inventory on home prices.

The Freddie Mac Home Price Index (HPI) for the country showed a 4.8 percent gain in the second quarter, the largest quarterly pickup in eight years. Year-over-year, the national index posted a 1 percent increase, the largest annual appreciation since November 2006.

Other HPI metrics also suggest a strengthening market, with CoreLogic’s index rising 2.5 percent year-over-year for June and FHFA’s HPI posting year-over-year gains through May.

In addition, the recovery was broad-based. From June 2011 to June 2012, 34 states (and the District of Columbia) posted gains in home prices. This was the largest number of states reporting annual appreciation since April 2007.

Freddie Mac speculated that even if national HPIs dip in the usually weaker autumn and winter months, the second-quarter HPI gains will likely overshadow any expected declines.

While prices have shown positive growth in many states through this year, concerns about shadow inventory-the stock of single-family loans that are seriously delinquent— have some experts worried about prices taking another tumble.

Freddie Mac asserted that although delinquency rates may be higher than they were before the recession, the “shadow” over the housing market is not as long as some may think.

“While the shadow inventory persists, there is an important difference in today’s market compared with those of recent years, and that’s the substantially reduced amount of excess vacant housing,” said Frank Nothaft, VP and chief economist for Freddie Mac.

Vacancy data from the Census Bureau showed that vacancies in U.S. homes for rent or for sale continued to decline in the second quarter. Rental vacancy rates have fallen to 8.6 percent, the lowest rate since the second quarter of 2002. For-sale vacancy rates have dropped to 2.1 percent, the lowest since the second quarter of 2006.

Additionally, the for-rent market now appears to be in relative balance, with rental stock close to overall rental demand. This results in normal vacancy levels.

The continuing drop in excess vacant stock is important because it means that in most markets, REO homes on the for-sale market don’t have to compete with an oversized vacant inventory.

“The housing recovery may finally be coming out from the shadows,” Nothaft said.