Tenneco Inc. (TEN), the maker of diesel exhaust filters and mufflers, fell the most in six months after reporting profit that missed analysts’ estimates.

Tenneco dropped 10 percent to $32.50 at 10:13 a.m. in New York and earlier fell as much as 11 percent, the biggest intraday decline since Oct. 28. The shares had advanced 21 percent this year before today.

First-quarter net income fell 36 percent to $30 million, or 49 cents a share, from $47 million, or 75 cents, a year earlier, the Lake Forest, Illinois-based company said today in a statement. Excluding items such as 18 cents a share in financing costs, profit was 66 cents a share, compared with a 73-cent average of 12 analysts surveyed by Bloomberg.

Sales rose 8.6 percent to $1.91 billion, compared with $1.89 billion, the average of eight analyst estimates.

To contact the reporter on this story: Mark Clothier in Southfield, Michigan, at mclothier@bloomberg.net

To contact the editor responsible for this story: Jamie Butters at jbutters@bloomberg.net