** Software company NI Corp's shares NATI.O up 18.07% at
$47.43 - set for biggest single-day pct rise since March 2020
** Texas-based firm says it is exploring strategic options,
including a sale, amid interest from potential suitors
** Co says it is adopting a "poison pill", which would be
triggered if a person or a group's ownership reaches 10%; the
limit is 20% in case of passive institutional investors
** NATI stock lost 15.59% in 2022
(Reporting by Pratyush Thakur in Bengaluru)
((pratyush.thakur@thomsonreuters.com))