The royal palace announced on Sunday that the king, a widely revered figure who suffers from kidney failure and receives hemodialysis to filter his blood, was in unstable condition and that he was breathing with the help of a ventilator.

That was reiterated by the palace in a health bulletin issued Wednesday evening, adding that his blood pressure was low, his liver function was abnormal and he appeared to have a blood infection.

“The king is a father of the entire Thai people,” said Suwanna Kaennamtiew, 62, of Bangkok, who came to the hospital to pray for him. “We are living under his virtue. We love him very much. Nothing can compare to him.”

Like many of the king’s supporters, she was wearing pink to promote his well-being.

Throughout most of his reign, the king offered moral leadership and promoted economic development. A strict lèse-majesté law prohibits defaming, insulting or threatening the king, queen, heir-apparent or regent.

Most Thais have known no monarch other than King Bhumibol, who ascended the throne in 1946.

Rumors began circulating around noon that he was near death and then flooded social media. The Stock Exchange of Thailand fell 6.9 percent, although it recovered to close down about 2.5 percent. The Thai currency, the baht, fell about 1 percent against the dollar.