More than $1 trillion in U.S. real estate debt from the last decade’s property boom is starting to come due as oil prices stagnate, squeezing property owners in cities and towns centered around the energy business.

The 50 percent plunge in crude values since June is already dragging down property prices in Texas, according to Green Street Advisors LLC. Real estate investors are adjusting their underwriting across the state as they gird for contraction at energy companies, demanding higher yields on their investments, the property-research firm said.