NEW YORK (AP) — Shares of health insurers wavered in premarket activity Thursday after President Barack Obama made clear he is sticking to his goal of health care reform in a televised speech to a joint session of Congress Wednesday night. The final impact on the health care industry is still far from certain as legislators continue the debate. Analysts caution that the stocks will remain volatile until the debate ends. "He could've given the same speech in Iowa or New Hampshire two years ago," said Robert Laszewski, president of Health Policy and Strategy Associates, adding there were no new proposals. For health insurers and their shareholders, the uncertainty over reform has made for a roller coaster throughout the year, driving shares lower, then higher depending on which way the political wind blows in Washington. Stocks dove deeper than the broader market in early March, after Obama described reform as "a necessity we have to achieve." They have since mostly climbed as opposition grew in Congress to a proposed public health insurance plan that would compete with private insurers. Insurers that have large segments devoted to individual insurance or group coverage for small companies could be hurt by a public option. That would include WellPoint Inc. and UnitedHealth Group Inc. Health insurer stocks jumped last month after Obama said the public option represented "just a sliver" of the overall proposal for health care reform. They moved up again earlier this month on a report that Obama will not insist on a public plan. Obama remained open to discussion, but is not insisting on a public plan, saying in his speech that it is only a means to the end of providing more competition, and isn't crucial on its own. "It is only one part of my plan, and should not be used as a handy excuse for the usual Washington ideological battles," he said. Shares of companies including Minnetonka, Minn.-based UnitedHealth, Indianapolis-based WellPoint, Hartford, Conn.-based Aetna Inc. and their peers could advance on such comments, as they have in the past. The key concern, he said, is uncertainty over the public option. Without it, the requirement for all Americans to have health insurance could be a boon of up to $700 billion in new revenue for health insurers. But until Democrats pull it out the industry will likely remain uncertain over the potential impact of health care reform. The prospect of a public plan is receiving too much attention, according to Stifel Nicolaus analyst Tom Carroll said. "I don't know anybody who thinks the public plan is viable," he said. A bill currently proposed by the Senate Finance Committee does not include the option. Likewise, Wachovia analyst Matt Perry said in a Wednesday research note he believes the public plan will eventually be dropped from the reform push. Another potential boost for insurers could be strong wording around incentives for quality medical care, an idea supported by the insurance industry to help lower medical costs, including their own. Humana shares are up 26 percent over the last 13 weeks, while UnitedHealth shares gained 7 percent and Aetna shares have gained 21 percent over the same period. Overall, the majority of the nation's major health insurers have all posted gains over the last 13 weeks as debate over health care reform intensified, with many topping the 9 percent growth of the S&P 500. Meanwhile, the pharmaceutical industry stands to benefit from health reform increasing the number of Americans with insurance coverage, and so has been supporting reform in an ad campaign and in repeated comments from industry executives. Through their industry trade group, drugmakers agreed on June 20 to spend $80 billion over the next decade to cover half the cost of brand-name drugs for seniors on Medicare who hit the so-called "doughnut hole gap" when government assistance on prescription costs stops. Biotechnology companies have been mainly on the sidelines of health care reform, focusing their attention more on how the debate over regulating copies of biotech drugs will pan out. Hospitals could see some benefit if a significant boost in the number of insured people reduces the number of patients at urban and rural hospitals who aren't able to pay their bills. But it could be a wash if the federal government reduces subsidies to help hospitals that provide the most charity care — or if newly insured patients are in health programs that reimburse hospitals at the same rates as Medicare and Medicaid, which often do not completely cover patient costs.