LONDON — BP, the British oil company, reported a $1.4 billion loss Tuesday for the three-month period ended June 30. The main reason for the loss was $4.8 billion in write-downs on refineries, shale gas assets in the United States and a long-delayed project in Alaska.


The earnings will do nothing to assuage the concerns of investors, who are already discontented with the performance of the century-old company and its first American chief executive, Robert W. Dudley. BP’s share price was down 4 percent in afternoon trading in London.


“This is a very, very disappointing set of results; they missed across all fronts by a wide margin,” said Peter Hutton, an oil analyst at RBC Capital Markets in London. Stripping out the $4.8 billion in write-downs, BP’s results were still 17 percent below the consensus estimates of analysts, Mr. Hutton said.


According to Mr. Dudley, BP is writing off a combined $2.1 billion on shale gas acreage because of lower natural gas prices, as well as a project called Liberty on the North Slope in Alaska that BP invested in but then recently halted because of environmental and other concerns. The remaining $2.7 billion is a write-down on the value of BP’s U.S. refinery system. The company is trying to sell two of its U.S. refineries, including a giant one in Texas City, Texas, and has come to realize from other sales that they are not worth the value it had on its books.


Mr. Dudley is caught between pressure from investors who want to see an improvement in the stock price, which is still down about 30 percent from the level at the time of the disastrous Gulf of Mexico oil spill in April 2010, and his own determination to make BP a safer, more reliable and ultimately more profitable company. Unfortunately, such a transformation requires time and weighs on performance in the short term as oil fields are shut down for extensive repair work.


“Managing competing priorities is always a problem,” Mr. Hutton said. “If you want to be thorough and make sure everything is right, it is a major, major exercise.”


Mr. Hutton said that to convince investors he was on the right track, Mr. Dudley needed to demonstrate that costly shutdowns in the Gulf of Mexico, where BP has much of its most profitable oil, were nearing an end.


The Gulf of Mexico has been a two-edged sword for BP. The 2010 spill has already cost the company $38 billion in charges, including an additional $847 million this quarter, and even threatened its existence at one point. But BP has also been the leader in developing deepwater oil fields in the Gulf, and these properties produce some of the most profitable oil in the company’s portfolio. Production in the Gulf has dropped sharply in the past two years because of the need for repairs and a halt to drilling that is now resuming. BP’s oil production in the United States was down a huge 25 percent compared with a year earlier to just 350 million barrels per day.


During a telephone call with reporters, Mr. Dudley said two major Gulf of Mexico oil fields, Mad Dog and Atlantis, which he said were among “the most profitable fields in the world,” had been shut for major repairs. BP has been replacing the subsea infrastructure of Atlantis, which has long been the target of safety critics. In the quarter, 85,000 barrels per day of BP production in the Gulf of Mexico was offline, according to a spokesman, Robert Wine, who said that the two fields would be coming back in the second half of this year and that a new field, Galapagos, was ramping up.


While Mr. Dudley said the Gulf of Mexico work was nearing an end, repairs will now begin in the North Sea, where drilling is also very lucrative. “One of the things we are not going to do is drift off the path of focus on safety,” he said. “Stepping up the accelerator of performance in place of that is not going to happen.”


Mr. Dudley is trying to use the Gulf of Mexico disaster as an opportunity to streamline BP into a smaller but more profitable company. He wants to focus on high-risk, high-return exploration and difficult megaprojects like those in deep water. Since the beginning of 2010 BP has sold about $24 billion worth of oil fields and other assets that it deems nonstrategic, and plans for the total to reach $38 billion by the end of 2013. It has cut overall production, excluding its TNK-BP Russian affiliate, to about 2.3 million barrels per day from about 3 million barrels per day in 2009. “It is going to be value over volume,” Mr. Dudley said.


His most important move in this regard is his plan to sell its 50 percent stake in TNK-BP. BP is negotiating with both its Russian partners and the state oil company Rosneft to dispose of the stake, which analysts think could bring $20 billion to $30 billion.