Samsung Electronics shares have suffered their biggest fall in a single day in almost four years, after a US jury found the technology giant copied designs from Apple.
The South Korean company’s shares fell 7% in Seoul trading, the most since October 2008.
The company was ordered to pay $1.05 billion in damages to Apple, in one of the most significant rulings in a global intellectual property battle.
Samsung will appeal over the verdict.
Analysts said investors were worried that the ruling could affect revenues.
“An adjustment in the next few days is unavoidable as the damage amount was much bigger than market expectations, and there are further uncertainties, such as the possibility of a sales ban,” said John Park, from Daishin Securities.
Apple has said it will seek an injunction to block sales of Samsung products in the United States, a key market, at a court hearing on 20 September.
One of the biggest concerns for Samsung is whether Apple will now target the Galaxy S3, which was not included in the recent trial, as it focussed on older products.
The flagship product is Samsung’s best selling smartphone and if it is included in a US ban on sales that would give Apple a major advantage in the market, analysts said.
A nine-member jury in San Jose, California ruled on 24 August that Samsung had infringed Apple patents for mobile devices.
It was the most closely-watched of many similar patent disputes being contested in courts around the world between electronics manufacturers.
In recent weeks, a court in South Korea ruled that both Apple and Samsung had copied each other, while a British court dismissed claims by the American company that Samsung had infringed its copyrights.