New York CNN Business  — 

The Tariff Man is back. President Donald Trump’s newly proposed tariffs on China would be particularly bad news for US consumers.

Investors sold off well-known retail and tech stocks in response, because they would get hit hardest by the additional tariffs.

“Tariffs are taxes on American consumers,” said Rick Helfenbein, president and CEO of the American Apparel & Footwear Association. “The president’s decision to proceed with adding these additional costs for hard-working American families is truly shocking.”

Trump tweeted Thursday that he’s proposing an additional 10% tariff on $300 billion’s worth of Chinese-made products entering the United States. That includes things like smartphones, toys, footwear and many other consumer goods.

Retailers were not pleased.

“American families shouldn’t be a pawn in this trade war,” said Hun Quach, vice president of international trade for the Retail Industry Leaders Association. “Today’s announcement only moves us closer to consumers bearing the brunt of the pain.”

The National Retail Federation said it is disappointed the administration is doubling down on tarrifs.

“These additional tariffs will only threaten US jobs and raise costs for American families on everyday goods,” said David French, senior vice president for government relations at the NRF. “The tariffs imposed over the past year haven’t worked, and there’s no evidence another tax increase on American businesses and consumers will yield new results.”

Investors weren’t happy either. Shares of Best Buy (BBY) plunged more than 10%. Nike (NKE) was down 3%. Hasbro (HAS) fell 5% while rival toymaker Mattel (MAT) was down 7%. Apple (AAPL) fell about 2% while Chinese e-commerce giant Alibaba (BABA) was down more than 4%.

And the SPDR S&P Retail ETF (XRT), which counts Dillard’s (DDS), Abercrombie & Fitch (ANF), Guess? (GES), L Brands (LB) and Kohl’s (KSS) among its top 10 holdings, lost about 3%. Target (TGT) was down 4%.

“Uncertainty will dampen business investment and trade flows,” said Elena Duggar, Moody’s associate managing director.

She said American consumers will pay higher prices for everyday items, such as electronics, clothing, footware and toys, because of the tariffs.

Semiconductor stocks, which have a big presence in China, also plunged due to worries that China could retaliate with further tariffs against the US tech industry.

The Philadelphia Semiconductor Index (SOX) fell 2%, led by drops in Intel (INTC), AMD (AMD), Nvidia (NVDA), Qualcomm (QCOM) and Broadcom (AVGO).

That led to a dramatic turnaround on Wall Street Thursday, with the Dow swinging from a 300-point gain earlier in the day to a more than 250-point loss.