Semiconductor stocks were recently in the midst of a historic run, a winning streak that is every bit as impressive as Joe DiMaggio’s famous stretch of 56 straight games with a hit.

Okay, we may be exaggerating a bit. The iShares Semiconductor exchange-traded fund (ticker: SOXX) was up for only 18 consecutive trading sessions, including Friday’s nearly 5% pop on the back of Intel’s solid earnings and an analyst upgrade for Intel rival Advanced Micro Devices. But you catch our drift. The streak ended Monday, though, as the ETF fell 1.3%.

The big question now is whether investors should keep chasing chip stocks. After all, the ETF has now soared nearly 50% since March 30.

It may be time for investors to cash in on some of those gains. The SOXX ETF now trades at nearly 26 times forward earnings estimates, well above its 10-year average price-to-earnings ratio of around 19, according to FactSet. What’s more, the ETF has typically traded at a slight discount to the broader market, but it’s currently fetching a 17% premium to the S&P 500.

Investors are pricing in perfection. Strong results from Intel and Texas Instruments this week are helping for now. But Steve Sosnick, chief strategist with Interactive Brokers, worries that “a big risk now is that expectations become too lofty for companies to exceed.”

Also, good luck trying to find any chip stocks that have sat out this explosive rally. The “worst” performer in the SOXX ETF since March 30 is Qualcomm —and it’s still up 16%.

Nvidia, the world’s most valuable company, is up “just” 22%, making it a laggard as well. Credo Technologies, Astera Labs, and Intel are the ETF’s biggest winners. All three have doubled during the winning streak. Intel is on track to close at an all-time high Friday. But Marvell Technology, AMD, Texas Instruments, Micron Technology, and Arm Holdings have all shot up more than 50% as well.

Bespoke Investment Group noted in a report Friday that the Philadelphia Semiconductor Index, which roughly mirrors the SOXX ETF and is also on an 18-day winning streak, could be looking stretched.

“There has only been one other 18-day period in the index’s history when it gained more, and that was coming out of the dot-com crash lows in Q4 2002,” Bespoke noted.

But there may be pockets of the chip sector that can continue to build on this wave of momentum, even though they have also shot up sharply.

Mizuho Americas tech sector specialist Jordan Klein pointed out in a report Friday that while Intel, AMD, and other central processing unit (CPU) stocks “get chased to no avail,” there may better bargains in memory chips due to the “CPU euphoria.” Despite big rallies of their own, Micron and Sandisk, for example, “still look way cheaper” than AMD, Arm, and Intel, Klein noted.

Micron trades for just 6 times earnings estimates for the next 12 months and Sandisk has a P/E of around 10. AMD, Intel and Arm, on the other hand, trade for 42, 74 and 103 times earnings estimates respectively.

These sky-high valuations clearly haven’t been a hindrance for chip investors yet, though. As Mike O’Rourke, chief market strategist at JonesTrading, pointed out in a report this week, “there is no doubt that many semiconductor companies are years into a very strong growth cycle that’s driving record earnings. By and large, demand is expected to remain strong for the foreseeable future.” But he added that “people should not forget this is a cyclical business.”

“The fact that this cycle is the largest ever is an obvious benefit during the upswing, but it also brings risks when the cycle peaks,” O’Rourke said.

That’s all the more reason for investors in semiconductor stocks to tread cautiously. There’s no shame in locking in some of the big profits in chip companies now before an eventual pullback.