Chinese technology stocks fell Tuesday after China's cybersecurity regulator widened its review of several of the country's newest public companies.

Ride-hailing giant $DiDi Global Inc.(DIDI.US)$ shed nearly a third of its value since shares spiked as high as $18 apiece on June 30, the day of the company's public debut. Last week Chinese officials banned the company from adding new users and launched a probe of the company's data practices.

On Monday, Chinese officials announced similar probes into other newly public Chinese tech companies -- truck-hailing app $Full Truck Alliance Co. Ltd.(YMM.US)$ and an online recruiting app $KANZHUN LIMITED(BZ.US)$ -- sending shares of those stocks and countless others in the region sputtering. On Tuesday, Full Truck slid nearly 6.7% and Kanzhun fell 16%. $Baidu Inc(BIDU.US)$, $Tencent Music(TME.US)$, $JD.com Inc(JD.US)$ and $Pinduoduo(PDD.US)$ slid between 5% and 6.8%.

The latest regulatory actions and stock moves have confounded emerging-market investors, who say they feel stuck between balancing their bullish outlooks on the growth of Chinese tech stocks against increasingly aggressive regulatory attacks from both China and the U.S.

"I understand the market; investors hate uncertainty," said Brendan Ahern, the chief investment officer for KraneShares in New York, of the pullback in Chinese tech stocks. "But despite all the regulatory bark, there's been no real financial bite to it."

KraneShares runs several China-focused funds, including the $4.6 billion KraneShares CSI China Internet ETF, which tracks an index mostly composed of 51 Chinese internet-related stocks.

Shares of the fund have fallen 18% so far this year, including 5.2% on Tuesday. The fund doesn't carry any exposure to Didi and the other two stocks that had been recently targeted by regulators, so these losses are all tied to the broader losses across Chinese tech stocks.

• Mr. Ahern said he continues to paint an optimistic picture to clients around Chinese tech stocks, highlighting the country's strong run of economic growth and burgeoning urban middle class, and personally bought more shares of the KraneShares fund on Friday.

• Other investors also remain bullish, with firms like BlackRock Inc. recently saying Tuesday that it continues to favor a heavier exposure to China.

"We believe investors are compensated for these risks," BlackRock strategists said in a note that had highlighted the potential for further hiccups due to conflicts between the U.S. and China and China's high debt levels.

Still, many Chinese stocks have underperformed this year as investors contended with a broader shift away from expensive, high-growth stocks, as well as a variety of punitive actions from both Chinese and American regulators.

Those actions from Chinese regulators include the cancellation of Ant Group Co.'s initial public offering last year, a $2.8 billion fine on Alibaba in April for allegedly abusing its dominant market position and accusations that more than 100 apps have illegally collected and used personal data.

The U.S., meanwhile, has made plans to restrict trading in some Chinese stocks and continues to impose tariffs on goods, crimping Chinese imports.

If regulatory problems persist, emerging-market funds may become a tougher sell to investors. China looms large in most emerging-market funds and strategies. The $32.2 billion iShares MSCI Emerging Markets ETF, for example, has nearly 37% of its assets tied up in Chinese businesses alone, more than double its second-biggest exposure by country, Taiwan.

But while BlackRock's fund has held onto a slim gain this year -- it remains up 4.1% since the end of December -- shares lag behind the returns of most other markets, including the U.S.'s S&P 500, which is up 16% over the same period. Following several strong months of inflows, investors pulled roughly $546 million from emerging-market funds last week, the group's first stretch of outflows since early November, according to data from Refinitiv Lipper.

If anything, some analysts say investors in Chinese and emerging-market-focused funds are likely to see more volatility after several major index providers add Didi to benchmarks over the next several trading sessions, forcing the ride-hailing firm into several more ETFs and other funds.

FTSE Russell said it plans to add Didi to some global equity indexes on Thursday, including its FTSE All-World Index and the FTSE Emerging Index. S&P Dow Jones Indices said it plans to add Didi to benchmarks on Monday, while MSCI will put the stock into its China All Shares Index on July 15.

S&P declined to comment on whether those plans have changed, while MSCI and FTSE Russell didn't respond to requests for comment.

Write to Michael Wursthorn at Michael.Wursthorn@wsj.com