A report from eMarketer indicates that retailers are driving growth in online ad budgets. The research firm says the industry accounts for one in five online ad dollars, but marketers across sectors should take note of rising budgets – a cue that online ads are a competitive necessity.

According to the forecast, retailers will spend $5.73 billion in online advertising in 2011. This is up from $5.16 billion in 2010. The firm also expects that retailers' online budgets will continue to grow, exceeding $8 billion by 2014.

The retail sector may be leading in terms of online ad spend, but eMarketer anticipates that spending will increase across the board this year. Telecom companies will surpass $4 billion in spending, while financial services firms are expected to boost spending from $3.10 billion in 2010 to $3.34 billion. In addition, automotive companies will go from $2.84 billion to $3.24 billion, computing products will spend an estimated $2.84 billion (up from $2.58 billion) and travel will hit $2.95 billion in spending in 2011.

With these figures in mind, brands might want to invigorate their own online ad campaigns in order to maintain a competitive edge. Plus, the investment may pay off – a recent IAB report indicates that 2010 internet ad revenue hit a record-breaking $26 billion in 2010.