The move signals the end of Travis Perkins' relationship with Tavistock Communications.
Earlier this month, the firm appointed Dresdner Kleinwort Wasserstein as joint corporate broker, alongside incumbent HSBC, to handle the extra work likely to arise from its move into a higher index.
Travis Perkins has been widely tipped to join the FTSE 100 when the new list is published on 8 June. The company will also enter Morgan Stanley Capital International's (MSCI) European index on 30 May.
A move into the FTSE 100 and MSCI Europe is likely to substantially increase Travis Perkins' shareholder base, bringing in a large proportion of retail and pension funds.
Both charts are widely followed by investment funds, some of which invest entirely in these indices. Other actively managed funds use FTSE and MSCI indices as performance benchmarks.
Travis Perkins recorded a 17 per cent rise in pre-tax profit for the 2004 financial year. The company made £190.4m in 2004, up from £162.7m in 2003.
But in the last month the company has warned of a slowing down of consumer spending at the Wickes DIY chain it acquired this year.