By Donna Kardos Yesalavich Of DOW JONES NEWSWIRES NEW YORK (Dow Jones)--BP PLC's (BP, BP.LN) U.S. shares jumped Thursday afternoon after the oil giant said the flow of oil into the Gulf of Mexico stopped during a test to see whether a recently placed cap on the well can entirely seal it off. BP's American depositary shares closed up 7.6% at $38.92, the stock's highest level since June 4. After the stock hit a 14-year low in late June at $26.75, it has recovered 36% of its slide since the April 20 explosion of the Deepwater Horizon rig. The stock had been up through most of Thursday's session on hopes for the test, which had been delayed from earlier in the week, to begin. It moved higher after the company confirmed it began the test and jumped once BP said no oil was flowing out of the broken well into the Gulf of Mexico. BP emphasized that the purpose of the test is to find out how strong the well is. The company hopes the well is strong enough to keep oil sealed in underneath the cap. The test could take anywhere from six hours to two days, BP said. "The stock is starting to price in the fact that they are eventually going to get this leak stopped," said Andrew Fitzpatrick, director of investments at Hinsdale Associates. "They seem to be a little ahead of schedule with that." Citigroup Global Markets analysts said in a note to clients that "controlling the well and stemming the oil flow is critical in giving some closure on the extent of the spill and should allow the assessment of costs to begin." -By Donna Kardos Yesalavich, Dow Jones Newswires; 212-416-2188; donna.yesalavich@dowjones.com (END) Dow Jones Newswires July 15, 2010 16:17 ET (20:17 GMT)