HMV bid for Ottakar's gets review

Ottakar, a major bookstore retail shop in the UK, has announced that it will be merging with HMV, its largest competitor. But a group of small independent bookstores do not like this idea at all. These small stores feel that this could potentially create a monopoly by HMV bookstores. They have filed a grievance with the Forum of Private Business, which deals with such cases. Some believe that the level of competition will be lessened due to this merging. Ottakar has 137 stores across the UK and if this merge is successful then the new chain would control 23% of the UK market. Do you think that these small stores are overreacting? Is 23% really that much?