SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K Current Report Pursuant to Section 13 or 15(d) of The Securities Act of 1934 Date of Report (Date of earliest event reported): August 13, 1999 ............... VIALOG CORPORATION ................................................................................ (Exact name of registrant as specified in its charter) Massachusetts 333-44041 04-3305282 ..................... .................... .................... (State or other (Commission (I.R.S. Employer jurisdiction File Number) Identification No.) of incorporation) 35 New England Business Center, Suite 160 Andover, MA 01810 ............................................................................... (Address of principal executive offices) (978) 975-3700 Registrant's telephone number, including area code.............................. ................................................................................ (Former name or former address, if changed since last report.) Item 5. Other Events Approximately 26 of the Registrant's shareholders, including the Registrant's founder and largest shareholder, John J. Hassett (the "Participating Shareholders"), have recently agreed with the Registrant to voluntarily extend by 120 days the "lock-up" period applicable to certain of the Registrant's securities beneficially owned by Participating Shareholders. The original 180 day lock-up period expired on August 4, 1999. The extended lock-up period agreed to by the Participating Shareholders will expire on December 3, 1999. The extended lock up period applies to an aggregate of approximately 2,002,500 shares of the Registrant's common stock and options to purchase an aggregate of approximately 473,750 shares of the Registrant's common stock. SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned duly authorized. VIALOG CORPORATION Date: August 16, 1999 By: /s/ Kim Mayyasi ----------------------- Kim Mayyasi, President