Home price declines in many parts of the country at the end of last year left more borrowers with “upside-down” or “underwater” mortgages.The terms describe a situation in which a homeowner's mortgage is worth more than their home itself. As of the end of last year, 11.1 million properties – or 23.1 percent of homes nationwide – were in this situation, according to CoreLogic.While the problem was less common in Texas, where home prices have remained strong compared to much of the country, it still affected 10.4 percent of homeowners in the state. Another 5.6 percent of Texas homes were in near-negative equity. Both numbers represented statewide improvements compared to the last quarter.Those with negative equity often have difficulty refinancing, and need to sell their home through a short sale if they want to move.”Negative equity holds millions of borrowers captive in their homes, unable to move or sell their properties,” said Mark Fleming, chief economist with CoreLogic.Houston homes with negative equity may also turn into foreclosures, as some homeowners walk away from a loan they can't pay. According to the Houston Association of Realtors, foreclosures made up roughly 25 percent of home sales last month.