Tech stocks are powering this record-setting rally on Wall Street — but how long can it last?

After months of anxiety over tariffs, inflation, Middle East tensions and so much more, the S&P 500 and Nasdaq Composite have scaled yet another wall of worry — mounting a strong comeback and returning to record territory for the first time in months.

See: S&P 500 scores record high for first time in 4 months. What could push stocks higher from here?

Investors now wonder whether the new records signal the start of a longer-lasting rally in the U.S. stock market, or if it’s merely a short period of boom before the next big shakeout. For some strategists, the answer hides in one of the market’s most longstanding questions: How broad is the rally?

Technology stocks have been at the forefront of the market’s record-setting rally. The so-called Magnificent Seven cohort of megacap tech names — which includes Apple Inc. AAPL, Microsoft Corp. MSFT, Nvidia Corp. NVDA, Amazon.com Inc. AMZN, Google parent Alphabet Inc. GOOGL GOOG, Meta Platforms Inc. META and Tesla Inc. TSLA — have collectively added $4.7 trillion in market capitalization since the stock market’s April 8 closing low, bringing their total market value to nearly $18 trillion as of Friday afternoon, according to Dow Jones Market Data.

Also leading the gains on the S&P 500 SPX were shares of Coinbase Global Inc. COIN, which have surged over 140% since April 8, making it the top performer among the large-cap index’s 500 components. Following closely behind are shares of Seagate Technology Holdings STX and Microchip Technology Inc. MCHP, which also logged notable gains of over 100% in the same period, according to Dow Jones Market Data (see table below).

Beyond individual names, tech-related sectors have also stood out as the best performers on the S&P 500 since April 8. The S&P 500’s information-technology sector XX:SP500.45 has popped over 41% since early April, while the communication-services sector XX:SP500.50 is up nearly 28%, compared with the 24% gain for the broader index over the same period, according to FactSet data.

The strength in technology stocks has prompted many to question if the rally is being driven by a wide swath of stocks or just a powerful few. But the answer isn’t straightforward — and it depends on which measure of market breadth investors are looking at.

The New York Stock Exchange’s daily advance-decline (A/D) line — one of the most widely followed stock-market breadth indicators measuring the difference between the number of advancing and declining stocks — rose to an all-time high on Thursday, when the S&P 500 and the Nasdaq Composite COMP briefly tested their record highs for the first time in at least four months.

Tom Essaye, founder and president of Sevens Report Research, said that the new highs in the NYSE A/D line showed that the recent advance toward record territory is “broad-based,” and it should be considered “both historically healthy and likely sustainable.”

Strong returns in cyclical sectors since the April lows also suggest the record-setting rally isn’t entirely confined to megacap technology stocks.

The S&P 500’s industrials sector XX:SP500.20 has risen nearly 27% since April 8, while the financials XX:SP500.40 and materials XX:SP500.15 sectors are also up nearly 19% in the same period, according to FactSet data.

See: This outlook shows why investors should maintain exposure to the ‘Magnificent Seven’

However, although the NYSE A/D line shows positive breadth in the stock rally, the reading on the percentage of the S&P 500’s stocks trading above their 200-day moving averages offers reason for concern.

Only about 50% of the S&P 500’s stocks on Thursday traded above their 200-day moving averages (DMA) — well below the early-May highs, according to data compiled by Sevens Report Research.

Typically, a healthy market sees between 65% to 80% of the S&P 500’s stocks trading above their 200-DMA. The 200-day moving average is usually considered a key indicator for determining the overall long-term trends of a security.

“The divergence between the bullish NYSE A/D line reading and recently heavy action in the percentage of S&P 500 stocks trading above their 200-DMA is a source of concern that the rally off the April lows has been due to a combination of real strength in some corners of the market, but simply counter-trend, bear-market rallies in others,” Essaye said in a Friday client note.

“For the bulls, the best-case scenario is for the percentage of the S&P 500’s stocks trading above their 200-DMAs to rise beyond the May highs of 55%,” he added.

Meanwhile, the S&P 500 Equal Weight Index XX:SP500EW — which gives equal value to all of the stocks that are included in the S&P 500, regardless of the size of the company — has risen 18.7% since April 8. That compares with the 24% advance for the market-cap-weighted S&P 500 index in the same period, according to FactSet data.

See: What drove stock market’s record-breaking week? Don’t overlook growing rate-cut expectations.

“We do need to see continuation in the rally across some other sectors, besides just tech or communications,” Ben Fulton, chief executive officer of WEBs Investments Inc., told MarketWatch in a phone interview on Friday. But he added that Federal Reserve interest-rate cuts would still be “necessary for any of the lagging stock sectors that are dependent on debts and financing” to keep pace with technology stocks.

To be sure, investors have been growing more confident in the outlook for the U.S. economy ever since President Donald Trump softened his stance on sweeping tariffs and struck trade deals with some of the U.S.’s major trading partners, including China and the U.K.

Meanwhile, the likelihood of at least three quarter-point rate cuts from the Fed by year-end, signs that recent tariffs have not significantly impacted inflation, and easing tensions between Israel and Iran also lifted market sentiment.

U.S. stocks finished higher on Friday, with the three major stock indexes booking strong weekly gains. The S&P 500 rose 3.4% for the week, while the Dow Jones Industrial Average DJIA was up 3.8% and the Nasdaq Composite surged 4.3%, according to FactSet data.

See: Trump’s latest trade threat looms over Wall Street as investors celebrate stock market’s return to record territory