The globe's third largest agency holding company Interpublic Group was left reeling on Wednesday when news broke that another of its largest clients, Bank of America, is to defect to world number one, Omnicom Group.

According to a report recently published by Advertising Age, BoA ranks 88th among the USA's top one hundred advertisers, with a total measured media spend in 2004 of $398.5 million (€323.2m; £221.2m).

However, the loss is considerably greater, given that the figure excludes marketing promotions, PR, direct marketing and other below-the-line activities. The New York Times estimates the total account value at around $600m annually. IPG had sixteen disparate agencies working on the business.

Financial ratings analyst Standard & Poors was at the ready to implant its boot, voicing concerns about "Interpublic's near-term operating outlook and whether financial issues at the holding company could pose a risk to its ability to maintain existing clients and originate new business".

Once the world's biggest agency group, Interpublic has been beset by financial and operational problems since the summer of 2002, when accounting irregularities were uncovered that led to a string of earnings restatements.

Adding a drop of vinegar to Interpublic's open wound is the fact that not quite two years have elapsed since it wrested the BoA account … from Omnicom.

The returning prodigal will have a core team of eight executives devoted to the BoA business, coordinating the work of lead ad agency BBDO Worldwide with other Omnicom shops specializing inthe Hispanic market, customer-relationship management, media planning and buying, interactive marketing and events/sports marketing.

According to Omicom president/ceo John D Wren, the battle hymn is "communication, coordination, collaboration".

Data sourced from New York Times; additional content by WARC staff