Stocks just finished a month that could hold its own with some of the frothiest moments of the tech stock boom of the late 1990s.

The big picture: With the end of the Iran war seemingly close, the S&P 500 ripped to new records in May, as falling oil prices, easing interest rates and strong earnings results set off a blistering rally in AI-related tech shares.

By the numbers: The S&P 500 posted a monthly gain of 5.2%, closing the month with a series of record highs. With Friday's close, the blue-chip index notched its ninth-straight weekly gain. The Nasdaq Composite index rose 8.4% during the month.

State of play: The S&P 500 is now up 10.7% for the year — the information technology sector led the way with a 16% increase, thanks to contributions from nostalgia-soaked stocks like Hewlett-Packard Enterprise (up 50% in May), Sandisk (55%), Cisco Systems (32%) and Micron Technology (88% higher in May).

• Dell Technologies was the top-performing stock in the S&P 500 index, as the dot-com-era laptop giant more than doubled during the month, as its effort to refashion itself as a seller of servers for AI data centers gathered traction.
• Not far behind was another company once considered a tech dinosaur, NetApp. The data management hardware and software vendor — which made its debut as Network Appliance in 1995 — rose 57.3% in May — and 22.4% on Friday — after the company reported strong quarterly results Thursday. It was the best month for the stock since February 2000.
• Meanwhile, semiconductor shares — as measured by the Philadelphia Semiconductor Index, or SOX — posted a second consecutive month of astronomical gains. The SOX index rose a combined 69% in April and May.

Fun fact: The only other two-month period when the index rose that much was in January and February 2000, just before the dot-com boom peaked in March.

What they're saying: "The everything-semiconductors rally has allowed the Philadelphia Semiconductor Index to reach some of the most short- and medium-term overbought conditions since the 2000 period," technical stock analysts for JPMorgan wrote Thursday, noting that the "comparison raises immediate concerns about a 'bubble.'"

• They stressed, however, that while the recent surge in chip stocks has been extreme, the rally would have to persist for several more months "to match the extremes achieved in the late-1990s and 2000 period."

The bottom line: Nobody knows where we are in the AI-related market boom.

• But even outside of the special case of semiconductors, there are plenty of reasons — from rising margin debt to elevated valuations — to wonder whether the enthusiasm of the market is getting a bit out of hand.

Corporate profits are taking the largest chunk of America's total income since a brief period of the early 1950s, as the slice of the pie going to worker pay has shrunk to the thinnest on record.

Why it matters: It's another piece of evidence underscoring the current state of play in the American economy: Surging profits have buoyed stock markets while increasing pressure on an already cranky public.

What they're saying: "The trend predates the AI boom," wrote Wall Street Journal economics commentator Greg Ip. "The causes are complex and the implications sobering. You can be a red-blooded capitalist and still worry about the political stability of an economy in which ever more output flows toward shareholders instead of employees."

What to watch: Whether a rising tide of anti-billionaire sentiment among Americans translates into a political push to divvy up the fruits of the economy differently.