Seems like an extremely high figure doesn't it. But if you really think about it, it's the only aspect of your company that cannot be replicated by your competitors, that attracts true customer loyalty and that truly differentiates you from every one of your direct and indirect competitors.
You may have a better product, but that can be copied. You may have superior staff, but they can be enticed elsewhere. You may have the best business model, but there's nothing stopping your competition from using it. The only true differentiator that consistently keeps your customers coming back and brings in new custom is the experiences they've had with your brand, the conscious and sub-conscious connections and connotations they have of your brand from advertising, marketing and word of mouth and the expected value they will receive from your brand. This is where your company is different from every one else, and where you can create true market value.
This is why every strategic business decision made should be based around the question "What does this do for the brand?" Does it have the potential to weaken the brand? Such as bringing in a product extension that could go wrong, or signing up the wrong sponsor. Is it consistent with the brand? I.e. if the brand is based around innovation, would using outdated marketing techniques reinforce this image or damage it? Does it position the brand in the wrong market? Such as advertising a premium brand in a discount store etc.
Considering how much of your companies worth is incorporated in the brand, it's clear what the implications of making the wrong decision for your brand could be.