X0202 4 2005-12-31 0 0001000495 VISUAL NETWORKS INC VNWK 0001044321 MARXE AUSTIN W & GREENHOUSE DAVID M C/O SPECIAL SITUATIONS FUNDS 527 MADISON AVENUE, SUITE 2600 NEW YORK NY 10022 0 0 1 0 Common Stock 2005-12-31 4 J 0 1771591 0 A 3519203 I By Limited Partnerships Bond 1.45 2005-12-31 4 J 0 3857060 0 A 2005-08-09 2007-12-31 Common Stock 2660042 9661910 I By Limited Partnerships Warrants 3.8359 2005-12-31 4 J 0 157879 0 A 2002-03-25 2006-03-25 Common Stock 157879 157879 I By Limited Partnerships See footnote in Remarks. This is a joint filing by Austin W. Marxe (Marxe) & David M. Greenhouse (Greenhouse). They share voting & investment control over all securities owned by Special Situations Cayman Fund, L.P. (Cayman), Special Situations Private Equity Fund, LP (PE), Special Situations Technology Fund, L.P. (Tech), Special Situations Technology II, L.P. (Tech II) and & Special Situations Fund III QP, L.P. (QP), respectively. 1,277,401 Convertible Bonds convertible into 880,966 shares of Common Stock are held by Cayman, 2,135,340 Convertible Bonds convertible into 1,472,648 shares of Common Stock and 1,550,000 Convertible Bonds convertible into 1,068,965 shares of Common Stock are held by PE, 56,648 Convertible Bonds convertible into 39,068 shares of Common Stock and 73,643 Convertible Bonds convertible into 50,788 shares of Common Stock are held by Tech, 335,461 Convertible Bonds Convertible into 231,353 shares of Common Stock and 376,357 Convertible Bonds convertible into 259,557 share Common Stock are held by Tech II and 3,857,060 Convertible Bonds convertible into 2,660,042 shares of Common Stock are held by QP. Pursuant to that certain Exchange Tender Offer described in Schedule TO-I of Special Situations Fund III, L.P. (SSF III), as filed by SSF III with the Securities and Exchange Commission on November 17, 2005, SSF III transferred the securities included in this Form 4 to QP on December 31, 2005. The interest of each of Marxe and Greenhouse in the shares of Common Stock owned by Cayman, PE, Tech, Tech II and QP is limited to the extent of his pecuniary interest. This is a joint filing by Austin W. Marxe (Marxe) & David M. Greenhouse (Greenhouse). They share voting & investment control over all securities owned by, Special Situations Private Equity Fund, LP (PE), Special Situations Technology Fund, L.P. (Tech) & Special Situations Technology II, L.P. (Tech II), respectively. 122,356 Warrants are held by PE, 5,813 Warrants are held by Tech and 29,710 Warrants are held by Tech II. The interest of each of Marxe and Greenhouse in the shares of Common Stock owned by PE, Tech and Tech II is limited to the extent of his pecuniary interest. 1. This is a joint filing by Austin W. Marxe (Marxe) and David M. Greenhouse (Greenhouse). They share voting & investment control over all securities owned by Special Situations Cayman Fund, L.P. (Cayman), Special Situations Private Equity Fund, LP (PE), Special Situations Technology Fund, L.P. (Tech), Special Situations Technology II, L.P. (Tech II) &Special Situations Fund III QP, L.P. (QP), respectively. 586,725 shares of Common Stock are held by Cayman, 980,786 shares of Common Stock are held by PE, 26,019 shares of Common Stock are held by Tech, 154,081 shares of Common Stock are held by Tech II and 1,771,591 shares of Common Stock are held by QP. Pursuant to that certain Exchange Tender Offer described in Schedule TO-I of Special Situations Fund III, L.P. (SSF III), as filed by SSF III with the Securities and Exchange Commission on November 17, 2005, SSF III transferred the securities included in this Form 4 to QP on December 31, 2005. The interest of each of Marxe and Greenhouse in the shares of Common Stock owned by Cayman, PE, Tech, Tech II and QP is limited to the extent of his pecuniary interest. /s/ Austin W. Marxe 2006-01-04 /s/ David M. Greenhouse 2006-01-04