a public company does not have to report buybacks before they start buying shares.
However, they do have to disclose their intentions, and later, the details of purchases.
Usually in the quarterly reports and if they want to in a news release
SEC reporting companies
Purchases must follow Rule 10b-18, which protects companies from manipulation accusations if they:
• Buy at prevailing market prices
• Don’t dominate trading volume
• Limit repurchases to a certain percentage per day
Alternative Reporting companies can follow Rule 10b-18 but they do not have too