The stock hit an intraday high of $17.30 before it was briefly halted. Shares resumed trading roughly 11 percent up and ended trading nearly 13 percent up.
The Chicago Tribune, citing unnamed sources, reported at least two bids are on the table — one with a price tag between $19 and $20 per share. Politico reported a similar bid in July.
Tronc earlier this year sold the Los Angeles Times and a San Diego-based paper. It owns the Chicago Tribune and Baltimore Sun, among major papers.
With Wednesday's surge, the stock is up 22 percent in the last 12 months but down 5 percent in 2018.