The stock market ripped higher Wednesday -- and chip stocks are a poster child for the rally. When to buy them is more clear now.

The major U.S. indexes surged Wednesday, with the Nasdaq Composite up more than 12%. President Donald Trump announced a 90-day pause on reciprocal tariffs except for China, while keeping the baseline 10% rate on all imports to the U.S. in place. The announcement comes after data has showed that consumer and business confidence has plunged, which could portend a plunge in spending -- and a recession. Wednesday, the market is reflecting a slightly greater probability that the U.S. avoids recession.

The iShares Semiconductor ETF rose as much as 18% Wednesday to $183, after having fallen as much as 33% from its Feb. 19 level, when the broader market began to sell off. These stocks are often more volatile than the market because, when consumers and businesses stop buying chips, semiconductor manufacturers see a major hit to earnings. It takes much longer for chip makers to reduce production than it does for customers to cancel orders, so prices can tumble rapidly, pressuring semiconductor profit margins. So when the market reverses course -- thanks to Trump's tariff shift -- chip stocks jump back to previous price levels for massive gains.

Overall, there's good news and bad news. The bad news is that, if Trump doesn't hold his word, the chip ETF will drop harshly again. The good news: Investors now have an idea of what prices to buy at. Sure, $154 was its bottom since Feb. 19, and technicians will say that's a level traders should buy at. But the stronger case for buying these stocks is their valuation.

Before Wednesday's big rally, chip stocks looked truly cheap, even considering what's likely to be lower earnings estimates from where analysts have them penciled in today. While no one knows right now what trade policy will look like for the long term and the degree to which the economy will suffer, Alliance Bernstein analyst Stacy Rasgon put some numbers around earnings for chip companies.

He started by noting that after the Financial Crisis, chip analysts reduced sales expectations by 25%. Earnings estimates fell by about 50%. When revenue drops so harshly, profit margins drop because companies can't cut all costs.

But a tariff-induced recession likely wouldn't be quite like the financial crisis, so Rasgon posed a scenario in which analysts cut consensus sales projections by about 15%. Nvidia looked attractive before Wednesday's rally.

If analyst's 2025 sales projection for NVIDIA drops by 15% to $169 billion, its chip prices and gross margins would likely fall a bit. The company would cut some operating costs, but its net profit margin would still fall. In Rasgon's scenario, earnings per share would drop about 14% to roughly $3.80.

Even assuming this -- pretty close to a worst-case scenario -- the stock would still appear cheap at prices earlier this week. Nvidia closed Tuesday at $96, which was about 25 times those lowered earnings. The lowest multiple it has seen in the past three years was about 24 times, according to FactSet. After Wednesday's rally, shares are at $114, or 30 times those lowered earnings, right around the middle of its range for this year.

The point is that the outlook for chip stocks are moving into cheaper territory. The stock would continue to rally as Trump continues to negotiate. But if Trump disappoints and shares drop again, they will look highly attractive. Even if it dropped back to $96, Nvidia shares would be unlikely to drop much more. And if its Big Tech customers continue to increase their spending on data centers and chips as they build out their artificial intelligence capabilities, Nvidia's earnings would grow from any lower level this year. The stock would rally once again.

Get ready to buy chip stocks like Nvidia.