Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of onshore oil driller and oilfield service company Key Energy Services Inc (KEG -68.26%) are down about 5% this afternoon, after falling as much as 10% earlier today. So far this year, the company's stock has been all over the place: 

KEG Chart

KEG data by YCharts

So what: There isn't any material news out there about Key Energy Services directly, but there's a lot of bad news in general that indicates the driller will have plenty of tough days ahead of it. As the U.S. Energy Information Administration reported last week, global production continues to exceed demand, and this has led to record levels of U.S. crude inventories. 

This is further pushing crude prices down, with West Texas Intermediate -- a common benchmark for U.S. oil prices -- falling to levels we haven't seen since the heart of the economic crisis in 2009. This is even with the oil rig count as of March 13 reporting a 40% decline in active drilling rigs versus one year ago. 

Now what: Frankly, it's that last bit that's most concerning for Key Energy Services. It takes time for reduced drilling activity to impact production, and the longer production levels stay high, the longer the downturn would impact a company like Key Energy Services, which generates a lot of its business drilling wells. There isn't anything in today's news that is specific to Key Energy Services, but its core business is going to face serious pressure the longer oil production stays up, and oil prices stay down. 

Key Energy Services' stock price may be down 85% since the 2014 high, but this isn't likely the right time to buy. There are way too many questions about the future of drilling activity for the next year or more. I'd look for signs that oil production is stabilizing and the rig count decline is over before even considering investing in a drilling company.