A renewed drop in oil prices has put U.S. shale drillers at risk of losing crucial sources of funding.

According to Bloomberg, during Q1/15, U.S. drillers brought in $3.7 billion from futures contracts and other options purchased as insurance against falling prices last year. However, as Bloomberg notes, those hedges are starting to expire, leaving companies at risk of losing critical sources of income.

Now, bonds are much more expensive and riddled with burdensome terms. In addition, according to Bloomberg, of the $235 billion in debt owned by North American oil companies, $24 billion is trading at distressed levels.

Bloomberg also noted that in October, banks will reevaluate drillers’ lines of credit, putting these companies at further risk of losing important sources of funding.

Read the full Bloomberg report here.