US onshore players will face a more difficult time balancing their books in 2016 and more could fall into default on their loans and, in some cases, bankruptcy, warned a leading ratings agency.

Moody’s Liquidity Stress Index, a proprietary measure of the financial health of a group of companies, increased to 19.6% in December, up from 19.3% in November “as the rout in oil prices has continued to take a toll on liquidity and defaults,” the agency said.