The move follows the acquisition of Alban, which owns Concord, by Aegis-owned Posterscope in August.
Helix was launched in 2003 and will be closed by the end of the year. IPM and Concord will trade separately from the beginning of 2006.
A statement from the two companies said: "After two-and-a-half years of successful trading, this closure has been brought about by IPG's recently revised global policy on outdoor media planning and buying."
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