What: Shares of Fairmount Santrol (NYSE:FMSA) fell more than 21% in December as oil prices and the amount of active U.S. land rigs continue to decline. This past month's drop capped off a 69% slide for all of 2015.

FMSA Chart

FMSA data by YCharts.

So what: The deeper and deeper that cheap oil's teeth bites into the budgets of domestic oil and gas producers, the less and less they are budgeting for new wells. Without those wells, well, it's awfully hard for Fairmount and pretty much any frack sand producers to keep growing sales volumes and get favorable contract rates. This past quarter, Fairmount's sand volumes sales dropped 9%, which led to a 40% decline in EBITDA on a year-over-year basis. 

There are two silver linings to this weak environment. The first is that Fairmount and a small handful of players in this space have seen their total volumes decline less than total sand consumed by the oil and gas industry. This suggests that Fairmount is gaining market share. The other is that despite headline losses, the company is still generating enough cash flow to cover all its spending needs and can tuck some cash away to weather this storm. 

Now what: If the company truly is capturing greater market share and is still able to fend off any major credit risks with excess cash flow, then this month's decline may be a little overdone. Eventually, oil and gas drilling in the U.S. will pick back up, and with it will come higher frack sand demand. As long as it doesn't face any more setbacks, then it should have the legs to survive this market swoon and be an even stronger player when business picks back up again.