(For a Reuters live blog on U.S., UK and European stock markets, click LIVE/ or type LIVE/ in a news window) (Updates to market close) NEW YORK, Nov 18 (Reuters) - U.S. stocks lost substantial ground at the close of a see-saw session on Wednesday as investors weighed encouraging vaccine developments against surging COVID-19 infections and lockdowns. While all three major U.S. stock indexes closed in the red, surging Tesla Inc shares helped cap the Nasdaq’s loss. “It’s a confused market because portfolio managers don’t know which time period to focus on,” said Tim Ghriskey, chief investment strategist at Inverness Counsel in New York. “It’s this trade-off between the near term over the six to nine months of continued spread of the virus and the period after that when everyone’s vaccinated and the virus is eradicated.” “There’s a lot of issues out there but the decided bias has been toward value and cyclicals,” Ghriskey added. Pfizer Inc and its German partner BioNTech revealed a 95% success rate at the conclusion of their COVID-19 vaccine trial, just days after Moderna Inc announced a similar rate of success in preliminary data from its vaccine candidate. Market participants have been greeting vaccine developments with guarded optimism as global new infections soar to record levels, raising the possibility of increased restrictions as the economy struggles to recover from recession. The United States remains the country worst affected by the pandemic. Unofficially, the Dow Jones Industrial Average fell 345.91 points, or 1.16%, to 29,437.44, the S&P 500 lost 41.81 points, or 1.16%, to 3,567.72 and the Nasdaq Composite dropped 97.74 points, or 0.82%, to 11,801.60. Third-quarter reporting season has reached the final inning, with 468 of the companies in the S&P 500 having reported. Of those, 84.4% have surprised consensus to the upside, according to Refinitiv. Boeing Co initially provided the biggest lift to the Dow after the Federal Aviation Commission green-lighted the planemaker’s grounded 737 MAX aircraft to resume flights, but its shares later reversed course. Shares of Target Corp advanced after handily beating quarterly profit and sales estimates, which were boosted by a 155% jump in comparable digital sales. Lowe’s Companies Inc dropped after the home improvement retailer forecast lower-than-expected holiday quarter earnings as it beefs up its online business and doles out employee bonuses to ease pandemic-related hardship. (Reporting by Stephen Culp; Editing by Tom Brown)