South Korea’s special prosecutor is due to decide whether to seek an arrest warrant for Samsung chief Lee Jae-yong.
Lee is a suspect in a corruption scandal surrounding South Korea’s impeached President Park Geung-hye.
He was questioned for more than 20 hours at the prosecutor’s office in Seoul last week.
Samsung is accused of giving donations to non-profit foundations operated by Choi Soon-sil, a friend of Ms Park, in exchange for government favours.
The donations were allegedly made in exchange for political support of a controversial merger.
Lee, also known as Jay Y Lee, is currently vice-chairman of Samsung Electronics. Since his father, Lee Kun-hee, suffered a heart attack in 2014, he is considered de facto boss of the entire Samsung Group conglomerate.
The decision on whether to formally arrest Lee had been delayed over the weekend.
Shares of key companies appeared unaffected on Monday. Samsung Electronics was up by 0.6% at the start of the trading session.
Samsung C&T shares were unchanged. That is the parent company which engages in overseas sales operations.
In the broader market the Kospi index in Seoul was up by 0.1%, reports the BBC.