Hoepli and Trecani dictionaries give a possible definition of "exponent" as items. Hence, my deduction, as preparers of financial statements, like many other professionals in Italy, use a flowery and often abstruse linguistic formulations for common terms Here I believe "voci" would have sufficed. You might want to wait for further input, as I'm deducing this from the little context given.

In the absence of context to understand what it is about.

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Note added at 3 hrs (2012-04-03 16:39:07 GMT)
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With an extract of an extract, you are really shooting in the dark. An "esponente" is usually an important person in a company. But what is the distinction they are making? If the distinction s it between customes and people in the company, albeit important, then you can just call them personnel, even if you have used that term for "il personale" and for "risorse umane". Whatever translates the meaning of the sentence, regardless of the individual words.

BTW if you Google on parts of the text, you will probably find the financial report already published on the Internet or if not last year's one.