Restricted stock, also known as restricted securities, is stock of a company that is not fully transferable (from the stock-issuing company to the person receiving the stock award) until certain conditions (restrictions) have been met. Upon satisfaction of those conditions, the stock is no longer restricted, and becomes transferable to the person holding the award. Restricted stock is often used as a form of employee compensation, in which case it typically becomes transferable ("vests") upon the satisfaction of certain conditions, such as continued employment for a period of time or the achievement of particular product-development milestones, earnings per share goals or other financial targets. Restricted stock is a popular alternative to stock options, particularly for executives, due to favorable accounting rules and income tax treatment. Restricted stock units (RSUs) have more recently become popular among venture companies as a hybrid of stock options and restricted stock. RSUs involve a promise by the employer to grant restricted stock at a specified point in the future, with the general intention of delaying the recognition of income to the employee while maintaining the advantageous accounting treatment of restricted stock. in venture capital–backed startups may include the following: A period of time before vesting, intended to prevent employees from "walking away" from the venture. There is generally a one-year "cliff" representing the formative stage of the company when the founders' work is most needed, followed by a more gradual vesting over a four-year schedule representing a more incremental growth stage. Founders are sometimes permitted to recognize a portion of the time spent at the company before investment in their vesting schedule, generally from six months to two years. "Double trigger" acceleration provision, stating that the restricted stock vests if the company is acquired by a third party and the employment of the grantee is terminated within a certain time frame. This protects employees from losing the unvested portion of their equity share award in case the employees are forced out by new management after a change in control. Another alternative is "single trigger" acceleration under which the change of control itself accelerates the vesting of the stock, but this structure is more risky for investors because following an acquisition of the company, key employees will not have any equity award that provides a financial incentive to remain with the company. "Market standoff provision", stating that holders of restricted stock may not sell for a