Houston-based McDermott International (NYSE:MDR) shares sank into a Marianas Trench-sized hole Monday, when after-hours traders, learning the extent of the company's Q2 2013 shortfall, bid the stock down nearly 15%.

Earnings at the offshore oilfield services company reversed completely, from last year's $0.22-per-share Q2 profit to a $0.63 quarterly loss this year. Revenues, at $647 million, tumbled 28% year over year.

Explaining the revenue decline and lack of profits, McDermott pointed to "the completion of several significant projects" in the Middle East and Asia-Pacific segments "that were active in the 2012 second quarter," but are so no longer. Higher revenues from the company's Atlantic segment weren't high enough to offset the declines elsewhere.

Project backlogs are also down to $5.1 billion, from $5.3 billion just a few months ago, suggesting further revenue declines could await investors going forward.