China Everbright Securities has suspended trading in the afternoon session Friday after domestic indexes spiked dramatically around 11:00 a.m. this morning.

Shares of the company soared 6.69 percent to close at 12.12 yuan at suspension. Major A shares witnessed a skyrocket of around 5 percent in the morning session, led by major financial stocks, before falling back.

Shares of the Industrial and Commercial Bank of China were up 4.05 percent and the AgBank rose 4.84 percent while Minsheng Bank soared by 8.21 percent ending 11:30.

Among the rumors circulated in the market is a speculation that traders at the securities firm had mistakenly handled deals of up to 7 billion yuan, leading to the snafu. A senior official with the brokerage has denied the rumor.

The Shanghai Stock Exchange has said it is investigating the incident but denied it was the result of a computer error at the exchange. Speculations as to the cause also include upcoming favorable policies and a 5 billion yuan worth of "oriented stimulus".