What Is a Quiet Period?
Before a company’s initial public offering (IPO), the quiet period is an embargo on promotional publicity mandated by the U.S. Securities and Exchange Commission (SEC). The quiet period prohibits management teams or their marketing agents from making forecasts or expressing any opinions about the value of their company. For publicly-traded stocks, the four weeks before the close of a business quarter is also known as a quiet period.

KEY TAKEAWAYS
A quiet period is a set amount of time when a company's management and marketing teams cannot share opinions or additional information about the firm.
The purpose of the quiet period is to preserve objectivity and avoid the appearance of a company providing insider information to select investors.
With an IPO, the quiet period stretches from when a company files registration paperwork with U.S. regulators through the 40 days after the stock starts trading.
With publicly-traded companies, the quiet period refers to the four weeks before the end of the business quarter.
The JOBS Act created a class of companies—emerging growth companies—doing away with specific quiet periods, notably the 25-day research quiet period.