Trading in OTCQX, OTCQB and Pink securities may take place Monday-Friday from 6:00 AM to 5:00 PM. The majority of quoting and trading occurs between the open market hours of 9:30 AM to 4:00 PM (Eastern); however, market participants are free to quote and trade at any time as long as they comply with current regulations (e.g., FINRA Best Execution). For updates on holidays and hours.
https://www.otcmarkets.com/learn/faqs