The last time the stock market had this long a winning streak, Twitter shares weren’t even a part of it yet.
Yet another gain for stocks on Thursday sent the Standard & Poor’s 500 index higher for an eighth straight day, its longest winning streak since July 2013, months before Twitter shares started trading publicly. It’s the latest step higher for a market that’s methodically climbed to record after record for much of this year as both the economy and corporate profits improved.
The S&P 500 rose 0.6 percent, to 2,552.07. The Dow Jones industrial average gained 0.5 percent, to 22,775.39, and the Nasdaq rose 0.8 percent, to 6,585.36. All three indexes added to records set a day earlier.
So many moves higher actually have some investors a bit nervous, because even the healthiest markets tend to have sharp sell-offs from time to time. The last time the S&P 500 had a pullback, of just 5 percent, was more than a year ago.
‘‘What’s really troubling most people more than anything is that we just go straight up,’’ said JJ Kinahan, chief strategist at TD Ameritrade. ‘‘There hasn’t been a pullback. That’s what most on Wall Street are trying to come to grips with.’’
Encouraging reports on the economy have been helping stocks, and on Thursday they included a stronger-than-expected rebound in US factory orders in August and a drop in the number of workers applying for unemployment benefits last week.
Friday’s report from the Labor Department on monthly job growth will likely show momentum in the opposite direction, with most economists forecasting a drop-off in hiring. But that’s mostly because of the recent hurricanes.
Netflix had the biggest gain in the S&P 500 Thursday, 5.4 percent, after it raised the price on its most popular US video-streaming plan by 10 percent.
Constellation Brands reported stronger earnings and raised its profit forecast; the company has been focusing on the higher end of the beer, wine, and spirits markets. The stock rose 4 percent.
On the losing end was student-loan servicing company Navient, down 14.3 percent. It said it was buying Earnest, a lender, for $155 million and would suspend its stock buyback program through 2018. Pennsylvania’s attorney general also alleged in a lawsuit that Navient improperly added billions of dollars in costs to borrowers.