This excerpt taken from the PCR DEF 14A filed Apr 17, 2009.
The Shareholders Agreement provides that for six months after the completion of the merger, none of the Tutor group shareholders may transfer or dispose of the shares of Perini common stock acquired pursuant to the merger other than to certain affiliated persons or pursuant to the exercise of piggyback registration rights described below following the decision by Perini to register shares of common stock.
After the six-month anniversary of the completion of the merger, the Tutor group will not be permitted to transfer shares of common stock unless after doing so they continue to collectively own at least 70% of the shares of Perini common stock acquired by them pursuant to the merger. This restriction on the transfer of shares continues until the later of the fifth anniversary of the effective time of the merger or the date on which the Tutor group owns less than 20% of the aggregate issued and outstanding shares of Perini common stock. After the fifth anniversary of the effective time of the merger or following the termination of Mr. Tutors employment without Cause pursuant to the employment agreement, such restrictions lapse and the Tutor group may transfer shares of Perini common stock so long as such transfers do not include a transfer of shares directly or indirectly equal to 15% of the total voting power of Perini to any person or group. In addition, all transfer restrictions under the Shareholders Agreement terminate on the date that is the later of the fifth anniversary of the completion of the merger and such time as the Tutor Group collectively ceases to own 20% of the aggregate issued and outstanding shares of Perini common stock. Notwithstanding the foregoing, the Tutor group shareholders may transfer or dispose of shares of Perini common stock in any transactions approved by a majority of the Board, excluding Mr. Tutor and the directors designated by him in his capacity as the shareholder representative.