(Bloomberg) -- China Ding Yi Feng Holdings Ltd. plunged 68% at the open on its first day of trading after a 10-month halt, wiping away a large part of a 8,500% rally that had confounded Hong Kong investors.

The stock in the obscure investment firm, whose assets are frozen, fell as much as HK$15.63 to HK$7.45 as trading resumed in Hong Kong, erasing HK$19 billion ($2.5 billion) in market value. After a rally that lasted five years, regulators halted trading in March last year amid suspected market manipulation.

As it announced a resumption in trading on Thursday, Hong Kong’s Securities and Futures Commission said in a statement that it will commence proceedings over suspected manipulation in the share against individuals linked to the company.

Before its suspension, the company had made its way into key indexes run by MSCI Inc. and the city’s Hang Seng Indexes Co. Ltd., attracting major funds like BlackRock Inc, Vanguard Group Inc. and State Street Corp. Both index providers have since removed the stock.

State Street and Vanguard declined to comment on a specific stock. BlackRock couldn’t immediately be reached for a comment.

The regulator also after the halt ordered nine brokers to freeze client accounts covering 32% of the issued shares of DYF, which are suspected as linked to the alleged market manipulation. Minority shareholders have criticized the regulator for not providing a good enough explanation for the halt in the shares.

The decline at the start of trading was widely expected.

“The bubble stock was suspended at $23.08 but net assets are just $0.07, so prepare for a spectacular, HK$28bn crash,” said David Webb, who runs an eponymous blog commenting on the markets.

It’s unclear if the SFC will pursue civil or criminal proceeding, Webb said.

“SFC has responded to the market’s demand on greater transparency,” said Gordon Tsui, chairman of Hong Kong Securities Association in a phone interview. “Investors would like to be well-informed before making decision to buy or sell. I believe this is a flexible and fair approach.”

Bloomberg LP, the parent company of Bloomberg News, competes with MSCI and others by compiling indexes and providing analytics for stocks, bonds and commodities.

To contact the reporter on this story: Kiuyan Wong in Hong Kong at kwong739@bloomberg.net

To contact the editors responsible for this story: Candice Zachariahs at czachariahs2@bloomberg.net, Jonas Bergman, Jun Luo

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