Oil is no longer spewing into the Gulf of Mexico -- at least temporarily -- as BP said it choked off the flow from its undersea well.
BP said it stopped the leak yesterday with the tight-sealing containment cap installed three days earlier.
Today the firm is waiting for the results of tests on whether the well remains intact.
That's a key issue as the British energy giant moves to plug the leak permanently with a relief well intended to intersect the ruptured well -- which extends 2.5 miles under the seabed -- and seal it with mud and cement next month.
BP's US shares closed up 7.6pc yesterday after it announced it had shut off the flow of oil from the well, and traders were eager to see if the rally would continue today.
Oil had spurted from the well a mile below the ocean surface for more than three months, causing a massive oil spill that led to an economic and environmental catastrophe along the US Gulf Coast.
"I think that it is a positive sign," said President Barack Obama, whose public approval ratings fell as the oil spill crisis dragged on.
He cautioned that "we're still in the testing phase".