Miniso Group Holding plunged as much as 16.7% on Monday after the company said it would take a stake in embattled Chinese supermarket operator Yonghui Superstores. The shares dropped another 5% in premarket trading Tuesday.

Miniso said it would take up a 29.4% stake in Yonghui for 6.3 billion yuan ($893.1 million) and will buy the shares from units of Singapore-listed DFI Retail Group and Chinese e-commerce giant JD.com at 2.35 yuan ($0.33) apiece, or a 3.1% premium to Yonghui's closing price on Sept. 20.

Nomura, which has a "buy" rating on Miniso, said the sudden acquisition of Yonghui brings notable uncertainties with no immediate synergy and the bold move may be too aggressive.

Yonghui has logged three years of net losses, reflecting mounting the costs of closing stores.

"We are sightly doubtful about the timing and the scale," CMB International wrote in a research note. "Using up 95%+ of its cash to buy an asset that is not profitable in the past 3 years does not look attractive at all financially, especially when the macro environment is still rather unclear."