A wobbly day of trading on Wall Street ended with most stock indexes managing slight gains, enough for the S&P 500 and Dow Jones Industrial Average to score all-time highs. The S&P 500 rose 0.1 percent after having been down 0.2 percent in the early going. The Dow Jones Industrial Average rose 0.2 percent and the Nasdaq slipped 0.1 percent. All three indexes started the day slightly in the green. The benchmark S&P 500 index, which also set a record highs Monday and last Thursday, has now posted 70 record highs for the year. In the post-World War II era, that’s the most new highs for the index since the 77 it set in 1954. The Dow last set a record high in early November. The major U.S. stock indexes are on pace to close out this year with strong gains. With two trading days left this year, the S&P 500 is …