Last year, United Airlines soared 27 percent, surpassing rivals as investors cheered a new management team’s turnaround plan. This year, shares are down 20 percent, the worst in the pack. The growing knock against United is that it’s trying to do too much, too fast. It’s growing aggressively. It’s waging fare battles against discounters, hindering a rebound in pricing power. It botched the rollout of a no-frills product designed to limit the pain from low-cost competition. The stock drop is adding to pressure on Chief Executive Officer Oscar Munoz and President Scott Kirby as they advance a $4.8 billion initiative to boost revenue, trim costs and catch up with the profit margins of Delta Air Lines Inc. While they have warned that the turnaround’s benefits won’t fully materialize until 2020, investors are losing patience as the company’s recent moves have undermined ticket prices and shares. “This is the right long-term strategy,” said John Tompkins, the founder of Tyvor Capital. “But what does that mean in the near term?”  The investment firm recently answered that question by selling all of its United Continental Holdings Inc. stock. Tyvor held 167,000 shares, valued at $12.6 million, as of June 30, according to data compiled by Bloomberg.  After falling five times more than a Standard & Poor’s index of the five biggest U.S. airlines this year, United fell Monday to the lowest price in 10 months. That means shares have given up all their gains since Warren Buffett’s Berkshire Hathaway Inc. said in November it had taken major stakes in the carrier and three competitors. Shares climbed less than 1 percent to $58.64 at 10:03 a.m. in New York. The slide accelerated in July when Chicago-based United said passenger revenue for each seat flown a mile could fall 1 percent this quarter and at best would inch only 1 percent higher. Now it seems even that glum forecast was too cheery for the closely watched gauge of pricing power. The company said this month that the slide would be as much as 5 percent. Transition Year Munoz and Kirby have cautioned that the benefits of their plan will take time to show up in the company’s results. “We continue to execute on the commitments we made to our investors, our customers and our employees, and we are making the right decisions today for the long-term success of United Airlines,” spokeswoman Megan McCarthy said by email. United has also said that the target for catching up with Delta’s profit margins is 2020, meaning it has time to deliver. “But clearly, there are people who are getting tired and worried about United’s execution,” said Savanthi Syth, an analyst at Raymond James Financial. “Clearly, there’s a loss of faith.” Most criticism is aimed at United’s rapid growth. Kirby, who joined the carrier a year ago from American Airlines Group Inc., has said previous management was too passive and gave up too much market share at its hubs. In response, United has started flying bigger, more comfortable planes to attract lucrative business travelers. It also has added flights. Market Size So have Delta and American. But they have focused on small and mid-sized cities, where the relative lack of competition prevents fares from dropping too low. United is set to grow 4.5 percent in the 25 biggest U.S. metropolitan areas this quarter, according to scheduling data analyzed by Raymond James. Delta is expanding capacity—a function of seats and miles available—only 1.3 percent in those markets, while American is shrinking a bit. “That’s where they’re probably being too aggressive, in the large markets,” Syth said. Another misstep: the rollout of a no-frills product known as basic economy. United, Delta and American all have introduced some form of the fares, which offer a cheaper price in exchange for fewer amenities. United’s version, for example, doesn’t allow carry-on bags. The idea is that the major airlines can compete with heavy discounters such as Spirit Airlines Inc. by offering a small number of basic-economy seats on each plane, without broadly matching the lowest prices throughout the cabin. But United rolled out the new fares relatively widely. While Delta used them selectively on competitive routes, United offered them even on flights that didn’t compete head-to-head with discounters, said aviation consultant Bob Mann. United also made too many of the fares available on any given plane, he said. ‘Additional Eyeballs’ “It never made any sense to roll it out in any place where you don’t have low-price competition,” Mann said. “You’re not going to get any additional eyeballs.” Indeed, the carrier found that given the option of buying a basic-economy ticket on United or a less-restrictive ticket on another airline, travelers chose the latter, Chief Financial Officer Andrew Levy told investors earlier this month. United since has reduced the number of flights, routes and seats on which the fare class is available. Former Spirit CEO Ben Baldanza, who sits on the board of Iceland-based discounter Wow Air Ehf, said United’s moves seem torn out of American’s playbook of two years ago. That carrier’s price war with Spirit and other discounters sent fares tumbling across the industry and touched off a two-year slump in pricing power that rewarded travelers while frustrating investors. Instead of a focused approach, United’s strategy is, “We’re going to kill every termite in the house,” he said.