BANGKOK - Thousands arrived in busloads to pray outside a Bangkok hospital on Friday for the swift recovery of Thai King Bhumibol Adulyadej, a day after concerns about his health sparked the biggest slide in a year in Thai stock prices.

As Thais queued up to sign get-well books at Siriraj Hospital where the world's longest-reigning monarch has spent the past 27 days, investors returned to Thailand's bourse, lured by bargains in a market that has jumped more than 50 percent this year.

Thai stocks ended the day up 3.5 percent.

Signs of economic recovery still continue, said Finance Minister Korn Chatikavanij, urging the public to disregard market rumors and attributing a seven-percent slide in the stock market on Wednesday and Thursday to foreigners cashing in after gains.

Investors nevertheless remain on edge despite assurances from policymakers and the palace itself which has said in brief, opaquely worded updates each evening that the 81-year-old monarch is on the mend after a bout of pneumonia.

Dutch broker ING advised clients on Friday to avoid Thai assets altogether.

Strict lese majeste laws in Thailand make comment on royal matters risky. But the king's disappearance from public view has raised concern in largely Buddhist Thailand where many of his subjects regard him as almost divine.

Most of the country's 67 million people have lived under his 63-year reign. The health of the king, Thailand's single unifying figure during a long series of military coups and constitutional experiments, is followed closely in financial markets.

Bhumibol's son and presumed heir, 57-year-old, foreign-educated Crown Prince Vajiralongkorn, does not yet command his father's popular support, raising concerns about succession in the powerful Thai monarchy.

A focus on the issue of royal succession would add another element of uncertainty to a polarizing four-year political crisis that has already hurt foreign investment in Southeast Asia's second-biggest economy.

STREET PROTESTS

In a vivid reminder of that crisis, thousands of red-shirted, anti-government protesters plan to gather in Bangkok on Saturday to demand the government submit a petition seeking a royal pardon for fugitive ex-premier Thaksin Shinawatra.

They hope clemency by the king would lead to his political return. Though a constitutional monarch seen as above politics, the king's influence over policy is seen as critical. Most analysts, however, doubt a pardon would be granted.

But for many Thais, the king's appeal is far simpler.

He is revered as the father of the nation and the longest-reigning monarch in Thai history, a figure of unassailable moral authority after decades of criss-crossing Thailand helping his subjects, especially the rural poor. At Siriraj Hospital, more than 10,000 Thais each day come to sign their name in get-well books or lay garlands in front of a monument of Prince Mahidol of Songkhla, the king's father, to pray for a speedy recovery.

Since he was admitted, 573,360 people have signed the get-well books.
Last night, I dreamed of the king and today I came here to pray for him, said Surin Namphosu, 58, from Sumut Prakan province, 127 km (79 miles) east of Bangkok, who is partially paralyzed and needed help to write her name.

I've wanted to come here for a very long time, she said.

Many well-wishers wear white, a lay Buddhist symbol.

I'm looking for the king and any sign that shows he is getting better, said Janyawat Uttathip, 41, as she looked up to the hospital's 16th floor were the king stays.

I listen to news about him all the time and feel relief when I hear that his health is in good condition. Being Thai, I always uphold the beloved king, she added.

(Editing by John Chalmers)

Thailand