More than nine out of every 10 mortgaged homes in the United States has positive equity, according to a recent report by the real estate data company CoreLogic. However, more than 4 million homes in the nation continue to have negative equity.

In its latest report on homeowner equity, CoreLogic determined that 759,000 properties regained equity during the second quarter of 2015. The company determined that 45.9 million residences, or 91 percent of all mortgaged homes, have equity. The estimated borrower equity among these properties was $691 billion in the second quarter of 2015.

Homes with higher values were more likely to have positive equity. Ninety-five percent of residences valued above $200,000 had positive equity, compared to 87 percent of those valued below this level.

"Home price appreciation and foreclosure completions both reduce the number of homeowners with negative equity, the latter because most homeowners who lost homes through foreclosure had some level of negative equity," said Frank Nothaft, chief economist at CoreLogic.

A total of 4.4 million homes, or 8.7 percent of all mortgaged properties, had negative equity. Under this condition, also known as being "underwater" or "upside down" on a mortgage, a borrower owes more on a mortgage than what the property is worth. CoreLogic says this condition occurs when a home's value drops, a borrower takes on more mortgage debt, or both situations occur.

The share of homes with negative equity has been decreasing. There were 5.4 million underwater homes in the second quarter of 2014, accounting for 10.9 percent of all properties. In the first quarter of 2015, 5.1 million homes—accounting for 10.2 percent of all mortgaged properties—had negative equity.

The total value of negative equity on underwater homes in the second quarter of 2015 was $309.5 billion. This figure marked a decline of $28.5 billion from the first quarter of the year and a $41.5 billion year-over-year decrease.

Fifty-four percent of this negative equity, or $168 billion, occurred on first liens with no home equity loans. First liens with home equity loans accounted for the remaining 46 percent and $142 billion.

Among the approximately 2.6 million borrowers with negative equity who had not taken out a home equity loan, the average mortgage balance was $239,000 and the value of the home was $64,000 under the mortgage amount on average. About 1.7 million borrowers had both first and second liens. This group held an average mortgage of $303,000 and was underwater by an average amount of $82,000.

Many homes had low levels of positive equity. About 9 million mortgaged properties, or 17.8 percent of the total, were considered "under-equitied" because they had less than 20 percent equity in their home. A total of 1.1 million, or 2.3 percent, had "near negative equity" of 5 percent or less.

CoreLogic says homeowners who are under-equitied will have a more difficult time refinancing their homes or getting new financing to buy another home. Homeowners with near negative equity are most at risk for going underwater on their mortgage if the home's value decreases.

Anand Nallathambi, president and CEO of CoreLogic, says home prices have been increasing steadily over the past three years. He says the company predicts that prices will increase an additional 4.7 percent in the next year, which could potentially allow another 800,000 homeowners to regain positive equity.

The report says Texas had the largest share of homes with positive equity, with 97.9 percent of mortgaged properties in the state worth more than what their borrowers owed on the home. Other states with large shares of positive equity included Alaska (97.6 percent), Hawaii (97.5 percent), Montana (97.2 percent), and Colorado (96.7 percent).

CoreLogic also looked at the 25 largest core based statistical areas to compare equity levels among large metro areas. Texas also had the metro area with the largest share of positive equity homes, with 98.1 percent of the properties in the Houston-Woodlands-Sugar Land region having values higher than their mortgages. In the Dallas-Plano-Irving metro area, 97.8 percent of homes had positive equity.

Other metro areas with the highest shares of positive equity were Portland-Vancouver-Hillsboro in Oregon and Washington (97.8 percent), Anaheim-Santa Ana-Irvine in California (97.5 percent), and Denver-Aurora-Lakewood in Colorado (97.5 percent).

The largest percentage of mortgaged homes with negative equity was in Nevada, where 20.6 percent of these properties were underwater. Other states with high shares of negative equity homes included Florida (18.5 percent), Arizona (15.4 percent), Rhode Island (13.8 percent), and Illinois (13.1 percent). CoreLogic says these five states make up 31.7 percent of all negative equity in the United States.

The metro area with the highest share of negative equity homes was Tampa-St. Petersburg-Clearwater in Florida, where 20.2 percent of mortgaged properties were underwater. Other metro areas with large shares of negative equity homes were Phoenix-Mesa-Scottsdale in Arizona (15.4 percent), Chicago-Naperville-Arlington Heights in Illiniois (15.3 percent), Riverside-San Bernardino-Ontario in California (12.3 percent), and Warren-Troy-Farmington Hills in Michigan (11.8 percent).