Stocks rose on Friday, capping the market’s best week in over a year and extending a rally that came as President-elect Donald J. Trump’s decisive election win put an end to months of uncertainty for investors.

The S&P 500 rose almost 0.4 percent on Friday, its fourth consecutive daily increase, and briefly crossed above 6,000 points for the first time ever. For the week, the index gained 4.7 percent.

Mr. Trump’s victory ushered in a relief rally that’s typical in the immediate aftermath of a presidential election as the vote becomes clear. Stocks were also buoyed by investors’ expectations of business-friendly policies under the Trump administration, including lighter regulation and tax cuts.

“The move this week in stocks was extreme, and speaks volumes about just how much the market loves having certainty,” said Clark Geranen, chief market strategist at CalBay Investments.

The Russell 2000, an index of smaller companies more closely tied to the ebb and flow of the economy, ended the week up 8.5 percent, its biggest weekly rise since April 2020 and the initial market recovery from the impact of the coronavirus pandemic. Sectors and companies that stand to benefit from Mr. Trump’s proposed agenda saw the biggest gains after his win, helping lift major stock indexes.

Tesla, the electric vehicle company run by Elon Musk, who in recent months has become one of Mr. Trump’s most prominent backers, saw its shares jump almost 15 percent on Wednesday in response to the election results. The company’s stock ended the week with a 29 percent gain, taking its market valuation above $1 trillion.