Enterprises involved in the cases would be fined 500,000 yuan ($78,000) each, it said, the maximum under China's 2008 Anti-Monopoly Law.
Alibaba, Baidu, JD.com and Geely did not immediately respond to requests for comment.
China has been tightening its grip on internet platforms, reversing a once laissez-faire approach and citing the risk of abusing market power to stifle competition, misuse of consumers' data and violation of consumer rights.
The earliest deal listed was a 2012 acquisition involving Baidu and a partner, and the most recent was the 2021 agreement between Baidu and Chinese automaker Zhejiang Geely Holdings to create a new-energy vehicle company.
Other deals cited by the State Administration of Market Supervision included Alibaba's 2014 acquisition of Chinese digital mapping and navigation firm AutoNavi and its 2018 purchase of a 44% stake in Ele.me to become the food delivery service's largest shareholder.
The deals, however, did not have the effect of eliminating or restricting competition, the regulator said.
In December last year, it fined https://www.reuters.com/article/us-china-antitrust-idUSKBN28O0CQ Alibaba, Tencent-backed China Literature and Shenzhen Hive Box 500,000 yuan each for not reporting past deals properly for antitrust reviews, the first time it had ever done so.
($1 = 6.3863 Chinese yuan renminbi)
(Reporting by Gabriel Crossley and Brenda Goh; Editing by William Mallard)
