MCI, Inc. (d/b/a Verizon Business) is an American telecommunications subsidiary of Verizon Communications that is headquartered in Ashburn, Virginia. The corporation was originally formed as a result of the merger of WorldCom and MCI Communications, and used the name MCI WorldCom followed by WorldCom before taking its final name on April 12, 2003 as part of the corporation's emergence from bankruptcy. The company formerly traded on NASDAQ under the symbols "WCOM" (pre-bankruptcy) and "MCIP" (post-bankruptcy). The corporation was purchased by Verizon Communications with the deal closing on January 6, 2006, and is now identified as that company's Verizon Business division with the local residential divisions slowly integrated into local Verizon subsidiaries.
MCI's history, combined with the histories of companies it has acquired, echoes most of the trends that have swept American telecommunications in the past half-century: It was instrumental in pushing legal and regulatory changes that led to the breakup of the AT&T monopoly that dominated American telephony; its purchase by WorldCom and subsequent bankruptcy in the face of accounting scandals was symptomatic of the Internet excesses of the late 1990s. It accepted a proposed purchase by Verizon for US$7.6 billion.
For a time, WorldCom was the United States' second largest long distance phone company (after AT&T). WorldCom grew largely by aggressively acquiring other telecommunications companies, most notably MCI Communications. It also owned the Tier 1 ISP UUNET, a major part of the Internet backbone. It was headquartered in Clinton, Mississippi, before being moved to Virginia.
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