EXHIBIT 2.1 AMENDMENT NO. 1 TO AGREEMENT AND PLAN OF MERGER AMENDMENT NO. 1 TO AGREEMENT AND PLAN OF MERGER (this "AMENDMENT") dated as of January 18, 2002, amends the Agreement and Plan of Merger dated as of October 25, 2001 (the "MERGER AGREEMENT"),...Agreement and Plan of Merger • January 22nd, 2002 • Jupiter Media Metrix Inc • Services-business services, nec • Delaware
