NEW YORK — Fifteen years after peaking during the dot-com boom, the Nasdaq composite has reached a new all-time high.

But this Nasdaq, while still focused on technology companies, is a little more diversified than it was back then. And while the index, which tracks 2,500-plus stocks, has been steadily climbing since 2011, its ascent isn’t the crazed surge that preceded its last record close.

During tech-mania, investors pushed up the prices of all kinds of internet-related stocks. Some were never profitable and disappeared. Others, like Priceline.com and Amazon, have survived and prospered.

Now the index has clawed back. It has ridden a six-year bull market for stocks to close at 5,056.06 on Thursday, surpassing its previous record closing high of 5,048.62, reached on March 10, 2000.

The headline number aside, the Nasdaq today is very different from the index and the overall market at the height of the technology boom, said Karyn Cavanaugh, a senior market strategist at Voya Investment Management. Investors have much more measured expectations of companies’ future earnings compared with the frenzied dot-com years.

Also, taking the effect of inflation into account, the index would have to reach 6,908 to match its highs from 15 years ago.

Here’s a closer look at the Nasdaq then and now:

The drivers

Now: The Nasdaq’s current rise has been driven by technology and health care. In a slow-growth world, investors favor industries where earnings will be better than average. Tech stocks are poised to benefit as companies increase their spending on equipment and software to cut costs and improve productivity. Health care stocks have been climbing as investors bet that biotechnology companies will discover the next blockbuster drug.

Together, tech and health account for almost two thirds of the Nasdaq’s market value.

Then: The Nasdaq had a much heavier tech-focus in 2000. At their peak, tech stocks made up 65 percent of the index compared with 43 percent today. Telecommunication companies were also a big component, accounting for 12 percent of the index’s market value versus 0.8 percent now.

Price-earnings ratio

Now: The price-earnings ratio of the Nasdaq, a measure of how much investors are willing to pay for every dollar of earnings the companies in the index generate, is 21.

Then: When the Nasdaq was at its highest, its price-earnings ratio reached 194.

Broader stock market

Now: Both the Standard & Poor’s 500 index and the Dow Jones industrial average are trading close to record highs from last month. The stock market is being underpinned by solid company earnings and optimism that the economy will continue to strengthen.

Then: The S&P 500 was also surging in 2000, rising with the internet bubble. The S&P 500 peaked at its then-record close of 1,527.35, on March 24, 2000. The Dow closed at a record of 11,722.98 on Jan. 14, 2000.

Nasdaq heavyweights

Now: Apple is the titan and Microsoft is a distant second with a market value of $356 billion. Google, Amazon and Facebook round out the top five. The top 20 also includes Starbucks, pharmacy benefits manager Express Scripts and retailer Costco.

Then: When the Nasdaq reached its record in 2000, Microsoft was the biggest company in the index, and the biggest 20 companies in the index were in technology or telecommunications.