The Dow Jones Industrial Average on Wednesday both crossed and closed above the 20,000 level for the first time, while the S&P 500 and Nasdaq Composite also cruised to records after upbeat earnings releases from heavyweights such as Boeing Co. and optimism over the economy.

The Dow Jones Industrial Average DJIA, +0.16%  surged 155.80 points, or 0.8%, to close at 20,068.51, with Boeing Co. BA, +1.05%  and Caterpillar Inc. CAT, -0.95%  contributing heavily to gains.

“Clarity is the markets’ oxygen. The more President Trump provides, the more Dow 20,000 moves to the rear view mirror — Dow 21,000 will soon become the next media obsession,” said Quincy Krosby, market strategist at Prudential Financial, in emailed comments. The new president has said he wants to cut corporate taxes and loosen regulations in moves that could potentially help corporate earnings.

Since the Dow first crossed 19,000 on Nov. 22, the biggest contributors to the blue-chip average’s quick 1,000-point rise were Goldman Sachs Group Inc. GS, +0.98%  (154.6 points), International Business Machines Corp. IBM, +0.21%  (90.6 points), Boeing (75.5 points), Walt Disney Co. DIS, +0.02%  (69.8 points), and UnitedHealth Group Inc. UNH, +0.94%  and Apple Inc. AAPL, +0.05%   tied at 56 points a piece, according to Dow Jones data.

Don’t expect, or hope for, 21,000 too soon however, said Ryan Detrick, senior market strategist at LPL Financial, in an interview. That would raise red flags of a top about to blow off. Plus, the February after an election has traditionally been the weakest month for the S&P 500 since 1950, he said.

The S&P 500 index SPX, -0.07%  gained 18.30 points, or 0.8%, to close at a record 2,298.37, with eight of the main 11 sectors trading higher. Financial and industrials shares were leading gains, while telecoms and real estate lagged behind.

The Nasdaq Composite Index COMP, -0.02% finished up 55.38 points, or 1%, at 5,656.34. The tech-heavy index has outperformed other indexes so far this year, gaining 5.1% year to date.

“What’s happening with earnings is driving gains, not just in the U.S., this is a global rally,” Detrick said.

Plus, resumed leadership from financial stocks and small-caps point to more positives than negatives, he added. The small-cap Russell 2000 index RUT, -0.49%  rallied 1%, while the Financial Select Sector SPDR ETF XLF, +0.25%  jumped 1.7%. Another cautionary signal would also be another big surge in the dollar, he said.

“The actual drive upward, and I don’t mean the unimportant level of 20,000 on the Dow, is being driven by a combination of better-than-expected earnings and especially outlooks from companies that suggest that economies in the U.S. as well as in Europe and Asia are in a better shape than we previously thought,” said Kim Forrest, senior analyst and portfolio manager at Fort Pitt Capital Group.

Earnings updates: Shares of Alcoa Corp. AA, -0.63%  closed down 2.6% Wednesday after the aluminum giant late Tuesday posted an upbeat forecast for 2017 aluminum demand.

United Technologies Corp. UTX, -0.54%  said its quarterly revenue growth was flat but reaffirmed its outlook for the year. Shares fell 0.6%.

Boeing Co. BA, +1.05%   shares leapt 4.2% after the aircraft maker reported much better-than-expected earnings in the final quarter of the year.

Texas Instruments Inc. TXN, +0.87%  gained 2% after late Tuesday reporting a rise in profit and sales for the fourth quarter.

Freeport-McMoRan Inc. FCX, -4.00%  shares fell 3.1% after the company reported fourth-quarter earnings that fell short of Wall Street expectations.

Other movers and shakers: Auto makers were among advancers on Wednesday, adding to gains from Tuesday when Trump told bosses of three Detroit car manufacturers he will work to ease environmental regulations and cut corporate taxes.

General Motors Co. GM, -1.99%  added 3.5%, Ford Motor Co. F, -3.28% gained 1.4% and U.S.-listed shares of Fiat Chrysler Automobiles NV FCAU, +0.73%  picked up 0.9%.

Ford is slated to release earnings on Thursday and here’s what to expect.

Cisco Systems Inc. CSCO, +0.13%  rose 0.3% after late Tuesday announcing an agreement to buy AppDynamics Inc. US:APPD  for $3.7 billion, just before the tech startup was set for an initial public offering.

Other markets: Stocks in Asia closed higher across all major markets and Europe SXXP, +0.25% followed the upbeat mood and finished in positive territory.

Oil prices CLH7, +0.17% LCOH7, +0.02%  settled down 0.8% at $52.25 a barrel after U.S. supply data showed a third week of rising inventories.

Gold prices GCG7, -0.45%  settled down 1.1% at $1,197.80, while the dollar DXY, +0.06%  fell against most other major currencies. The 10-year Treasury yield TMUBMUSD10Y, +0.46%  rose 6 basis points to 2.518%.

—Sara Sjolin in London contributed to this article.