The article investigates the sustainability of the pressure wielded by financial institutions and their responsibility for the sustainable development of other economic agents. As intermediaries, financial institutions often play a major role in the diffusion of sustainability: the assumption is that if the financial market is sustainable the real market will be even more sustainable. "Stock price premiums" are analysed for their potential distorted effects on competition. The comparison between the CSR investment capacity of large and small firms clarifies that one of the main reasons for aiming at sustainability should not be the possibility to obtain an incentive, and thus becoming more attractive for the shareholders who will own profitable stakes, but the gain in reputation which is in fact an economic incentive capable of increasing the profitability of responsible firms. "Stock price premiums" will be replaced by "sustainability chains" where sustainability-conscious clients will seek "committed" financial intermediaries who will attempt to establish relations with other sustainability-conscious firms.