HONG KONG (Reuters) – Shares of media group Next Digital Ltd (0282.HK) hit their highest since Sept. 2008 on Tuesday, spurred by an online campaign to show support for its detained owner, Hong Kong media tycoon Jimmy Lai.

At their height, shares rose 668.6% to HK$1.96 on Tuesday. They retreated to around HK$1.50, but still led gains on the Hong Kong bourse as the third most actively traded stock. Since the close on Friday, they have gained more 2,078%.

Police on Monday detained Lai, along with other executives of his media company in the highest-profile arrest under a national security law imposed by Beijing, which critics say crushes freedoms in Hong Kong.

Pro-democracy activists have started a campaign to encourage buyers for Next Digital shares and for the Apple Daily anti-government tabloid it publishes.

More than half a million copies of the paper were published on Tuesday, up from the usual 100,000. Buyers queued in the early hours and vendors had to re-order issues before the morning commute time.

One post on a local forum used by pro-democracy supporters said: “Freedom is priceless, use $$ to support Jimmy Lai.”

Next Digital’s market value has risen from HK$197.7 million ($25.42 million) early on Monday to HK$5.17 billion ($666.71 million).

The media group said in a bourse filing its operations have continued normally and it did not expect the arrests to impact its financial position.

Brokers said the surge was also driven by speculation Lai may sell the business.

“Speculation of sale of control and its low price level provided day traders a convenient excuse to bet on the stock,” a strategist from a local brokerage said, asking not to be named.

Another local media stock, Most Kwai Chung Ltd (1716.HK) has also jumped 292% so far this week.