Traders and financial professionals work on the floor of the New York Stock Exchange.

Check out the companies making headlines after the bell Wednesday:

Shares of Alcoa fell more than 5 percent in extended trading, after the company reported earnings and revenue that missed analyst expectations. The aluminum producer issued weaker than anticipated guidance for global demand growth, projecting 4.25 to 5.25 percent growth in 2018, compared to 5.25 percent growth in 2017, according to Thomson Reuters.

Shares of PTC soared more than 7 percent in extended trading. The software company reported first quarter earnings of $0.31 on revenue of $307 million. PTC results beat Wall Street estimates that projected earnings of $0.30 on $301 million, according to analysts polled by Thomson Reuters.

Plexus stock plunged nearly 6.8 percent, after the electronic components and systems manufacturer reported first quarter financial results. President and CEO Todd Kelsey attributed weaker than expected earnings to tax reform, citing $125 million in tax expenses.

"We are refining our capital allocation philosophy and plan, which we will share within the coming months," Kelsey said in a statement.

Shares of Apple nudged up slightly after the bell. The tech giant announced it would award eligible employees $2,500 in stock-based compensation. The news followed a rash of announcements from Apple that emphasized its commitment to the U.S. economy through foreign capital repatriation efforts and long-term economic contribution.