Gentex Corp posted a better-than-expected 58 percent rise in third-quarter profit on Wednesday and forecast a revenue increase of up to 35 percent for the fourth quarter, citing improving production volumes by automaker customers.

Shares of Gentex, which makes auto-dimming rearview mirrors and other auto parts, jumped nearly 19 percent.

Gentex said it was cautiously optimistic that the U.S. auto industry had seen the trough of a bruising downturn that had pushed major U.S. vehicle makers and parts suppliers into bankruptcies earlier this year.

Third-quarter net income rose to $23.9 million, or 17 cents per share, from $15.1 million, or 11 cents a share, a year earlier. Revenue rose 2 percent to $155.7 million.

Analysts on average expected Zeeland, Michigan-based Gentex to earn 12 cents per share on revenue of $137.8 million, according to Thomson Reuters I/B/E/S.

Gentex expects its revenue to grow 30 percent to 35 percent in the fourth quarter from a year ago as automakers rush to build inventories after steep production cuts in the summer.

Shares of Gentex were up 18.7 percent at $17.23 in morning Nasdaq trading. (Reporting by Soyoung Kim; Editing by Lisa Von Ahn)