Tullow Oil fell the most in four weeks in London trading after Investec Bank recommended investors sell the shares because of project delays in Uganda and Ghana.
Tullow slipped as much as 2.9 per cent, the biggest intraday drop since December 12, and traded at 1,250 pence as of 10.16am local time.
The stock lost 10 per cent last year.
Peak production at Tullow's Jubilee field in Ghana has been delayed for more than a year.
The lack of an agreement with the government of Uganda over a plan to develop a refinery and export-pipeline have held up the start of output from the East African nation.
"The delays across the production portfolio will in our view put upward pressure on Tullow's net debt and highlight the risk of further slippage," Brian Gallagher, a London-based analyst at Investec, wrote in a report.
He cut his recommendation on the stock to sell from hold and reduced the share-price forecast to 1,000 pence from 1,399 pence.
"We estimate a current capital expenditure bill in excess of $18 billion out to 2020," Mr Gallagher wrote. "
As a result, progress on disposals at Tweneboa-Enyenra-Ntomme (TEN) and possibly Uganda is required to help meet" funding needs.
Bloomberg
