Engineering company Willbros Group Inc. warned the downturn in its oil-and-gas business could lead to credit defaults that eventually may raise doubts about its ability to continue as a going concern. Shares of the energy-sector infrastructure contractor fell 51% to $2.70 in late-afternoon trading, after hitting an all-time low of $1.50 earlier. The company also said it expects to miss the deadline for its annual financial report. Houston-based Willbros said Tuesday that it is in talks with lenders to amend or get waivers on its credit agreements because the company expects to be out of compliance with certain debt-ratio requirements through next March. “The downturn in energy prices is clearly affecting our industry, and we have re-evaluated our outlook for 2015,” Chairman and Chief Executive John T. McNabb II stated in a news release. In a research note, Stifel Nicolaus said Willbros management sounded optimistic that the company could […]