Check out the companies making headlines in midday trading.

AMC — Shares of the movie theater stock sank almost 35% after a judge late Friday approved AMC Entertainment's plan to convert its preferred shares to common stock. AMC's preferred units, or APEs, surged about 17%.

PayPal — PayPal stock added 2% after the company announced Intuit's Alex Chriss would take over as chief executive beginning in September.

U.S. Steel, Cleveland-Cliffs — The steel maker founded by Andrew Carnegie and J.P. Morgan climbed nearly 32% after rejecting a buyout offer from peer Cleveland-Cliffs on Sunday, with the company asserting plans to consider other offers. Cleveland-Cliffs stock, meanwhile, climbed more than 8%.

Tesla — Shares slipped 2% after the company announced lowered prices on some models in China.

Hawaiian Electric — Shares plummeted more than 33% after Wells Fargo lowered its target price on the stock earlier and maintained an underweight rating Monday, citing wildfires in Maui as a looming risk.

Nikola — The stock lost 9% after the green truck maker announced a recall of 209 electric trucks following an independent investigation of a June fire. The company, which is coming off blows from complicated second-quarter earnings and news of a CEO departure, said this doesn't affect its hydrogen fuel cell trucks.

Okta — Stock in the identity management firm added 2.4% in midday trading after an upgrade to buy from Goldman Sachs over an improving risk/reward ratio.

Teledyne Technologies — The conglomerate climbed 4% after Goldman Sachs upgraded the stock to a buy from neutral. Goldman called the company a cash compounder.

— CNBC's Samantha Subin, Alex Harring, Pia Singh and Hakyung Kim contributed reporting.