Chinese beauty products e-commerce platform Jumei announced today it has fully acquired power bank rental company Ankerbox. The deal comes three months after the online retailer acquired a controlling 60& stake in the company for RMB 300 million ($45 million).

However, it seems that this isn’t a good time for Jumei to make huge exterior investments of this size given its own troubles caused by sliding performance.

Jumei’s investor Heng Ren Partners made public an open letter this Tuesday, firing shots directly at the company for full responsibility for the debacle over the past 18 months. To the benefit of investors, the firm asked Jumei to distribute a special dividend of $1.50 per share, which would total $225 million.

The letter pointed out that Jumei has suspended any meaningful communication with shareholders for 22 months. During the past 18 months, the market valuation of Jumei has slumped by $397 million, the firm pointed out. “An absurd amount considering the company’s current market value is $479 million,” said Peter Halesworth, Managing Partner in the letter.

Investing in non-core businesses was even cited as one of Jumei’s major missteps. In the wake of plummeting performance, the Chinese e-commerce firm has been adjusting its business model along nearly every hot e-commerce vertical. In addition to e-commerce related businesses, its investment goes broadly from film and television firms, air purifiers as well as power bank rental startups.

The company may consider these investments as new growth points, but its shareholder doesn’t see the point of making unrelated investments when they are already engaged in a burgeoning industry that’s been experiencing double-digit growth annually, especially when these investments are taking an unfair part of the company’s capital pool.

“The more than $59 million invested in these questionable non-core targets is equal to 12% of Jumei’s market cap, and 18% of its cash,” the letter pointed out.

Born out of an incubation project, Ankerbox is one of the top players in China’s heated power bank rental industry. The Shenzhen-based startup now operates in first- and second-tier cities, claims over 1 million daily users.