How does a professional investment banker (IB) create his brand or reputation? At the end of the day, he/his firm are judged by the client successes: type, size, industry, and niches within those industries. In other words, there are more than a few factors in play.
Some IBs are generalists, that is they handle clients across many industries. Others are very vertical in terms of industries served. For example, they work primarily for aerospace related firms.
Why do IBs focus on one or a few industries? They have decided to build a brand in a few verticals. By so doing, they know the most active buyers and sellers. And they learn the key metrics and issues, so they can present that they are experts in the prospect's business. For the most part, prospects tend to want industry-centric IBs.
The downside to this "expertise" is that industry familiarity may breed contempt. In other words, those whom are too close to the buyers may cut deals with and for them that are easy to achieve, but not in the best interests of their seller clients. Perhaps the price is too low or the terms not the best for the seller. These industry IBs are too often working on behalf of their buyer "friends," even though they actually represent the seller. In that case, "seller beware" of IB cronyism.