The S & P 500 rose more than 1% Friday afternoon after Iran said it would open the Strait of Hormuz for the duration of the ceasefire between Israel and Lebanon. The ensuing surge brought the index's gains over the past 13 sessions to more than 12%. But some investors on CNBC's "Halftime Report" on Friday were worried equities are moving higher too quickly, and are growing more cautious as the broad index's relative strength index hits 74, signaling it may be in overbought territory. "This is in the last 40 years, you've seen the quickest move from being oversold to overbought ," said Stephen Weiss, chief investment officer at Short Hills Capital Partners. The S & P 500 closed Thursday in overbought territory with its relative strength index rising above 70 just 12 trading days after the index closed oversold on March 30. That's the fastest such swing for the large-cap index since the early 1980s. The relative strength index, or RSI, is an indicator that measures the speed and magnitude of an asset's recent moves. A reading below 30 means that asset may be oversold, while a number above 70 means an asset may be overbought. .SPX mountain 2026-03-30 .SPX since March 30, 2026 chart. "Typically when that happens you see a pullback," Weiss said, referring to the swing from oversold to overbought. Jason Snipe, founder and chief investment officer at Odyssey Capital Advisors, said he's worried about breadth in the rally. The Invesco S & P 500 Equal Weight ETF (RSP) , which follows the broad market's equal weight counterpart, has underperformed since the market's bottom on March 30, up just over 8% in that timeframe. "I don't think that's healthy going forward," he said about the underperformance. "Too far, too fast is definitely a big deal for me… This move, although we're enjoying it for our clients as investors, is a little bit of a concern." .SPX .SPXEW line 2026-03-30 .SPX vs. .SPXEW since March 30, 2026. Markets have priced in a best-case scenario, said Jenny Harrington, CEO of Gilman Hill Asset Management. Even amid the most recent developments from the Middle East, she said the time has yet to arrive when economies would see reverberations — if they manifest at all — from the supply chain disruptions due to the military conflict that started at the end of February. Harrington said the short-term outlook remains cloudy, even if investors take ease from the latest headline. Amy Raskin said not to chase the rally. The chief investment officer of Chevy Chase Trust said investors are about to get inundated with headlines from earnings season, and high expectations means the bar for beats is higher. "Everybody just take a step back," she said. "We're going to get a lot of data and there's still a lot to parse through." — CNBC's Nick Wells contributed reporting
