In addition to the potential of a second competing offer being tabled, I would be betting that Lunit is currently buying On Market, and will continue to do so for some time (hence pushing the price up closer to Offer Price).
Any On Market price Lunit can get below the Offer Price of $1.15 is a big win for them, as they get to buy On Market for less than the Offer price and they also get to influence the shareholder vote in favour of their takeover.
VHT Price at posting:
$1.10 Sentiment: Buy Disclosure: Held