The complaint was part of the legal fight between the two fitness equipment companies that has escalated in recent months.
Peloton filed the complaint "based on Icon's fraudulent campaign to improperly acquire Peloton's trade secret advertising plans by soliciting the disclosures" from its advertising agency, according to Peloton's request for permission to file under seal, reported Bloomberg.
Peloton said that it will file a redacted public version of the complaint within seven days.
Last month, Icon Health filed a lawsuit against Peloton saying that the company infringed on a patent for a swiveling touchscreen and the ability to automatically switch resistance levels during classes.
Peloton sued Icon in May, claiming that the company copied its patented feature for making prerecorded online classes seem live.
Peloton said at the time that Icon “attempted to free ride off Peloton’s innovative technology.” Icon had previously sued Peloton when its first bike was launched and again when Peloton launched its first treadmill.
Peloton shares were down 1% to $99.84 in afternoon trading on Monday.