The supply crisis is hitting housing hard, as strong demand quickly eats up what few listings there are.

Home shoppers signed 0.5 percent more contracts to buy existing homes in December compared with November, according to a monthly pending home sales index from the National Association of Realtors. This was right in line with expectations. The index was also 0.5 percent higher compared with December 2016.

The supply of homes for sale at the end of December fell to the lowest level since the Realtors began tracking it in 1999. While new listings are already coming on ahead of the usually busy spring market, they will not come close to meeting the pent-up demand.

Read more in CNBC.