I think the trading floors (and ancillary arms) of this incarnation of the Stock Exchange have indeed shown us how many working within their portals (and financial sector in general) deviated from sound responsible activity when the prospect of great wealth was apparent and regulation lax.
We must never forget that we need a sound, imaginative financial sector but common sense dictates that this must be well regulated.
The original Financial Services Act was introduced in 1986 to counter an element of unregulated trading on the market floors. However, trading in those days was very simple...and thus easy to police, once the law was enacted.
Ironically, it was
not market floor trading that created the current problem but rather its successor - electronic trading. Once computers became widespread, trading became much cheaper (no need to pay commissions to "real people" on the trading floors), and much more accessible. Business thus mushroomed. On top of this, computing power enabled much easier and faster credit transfers around the world which, in turn, also led to increased business. Furthermore, derivative contracts - which (pre-computer days) would have required the establishment of a new trading floor - could now be set up cheaply within a short time frame on a server. Additionally, the old commodity futures markets - which featured contracts based on physical supply - soon became eclipsed by new cash settlement contracts in financial securities; initially gilts, bunds and the like, but latterly in debt instruments.
Around the turn of the millennium, banks and non-banking financial institutions began to hire "geeks" to devise computer trading programs which analysed risk/return characteristics and effectively did the necessary buying/selling without human interference. Indeed, it has been suggested that one such algorithm, used on Wall Street, had a defective risk element which contributed to the credit crunch.
IMHO, it was not greed that caused the problem, but rather the technological explosion. The industry became too vast, and too complex, to be adequately controlled using the methods envisaged by the FSA, the SEC and other regulatory bodies.
The endless polemics on here, based as they are on a class war against 'upstart bankers greedily fleecing the people' neatly avoids a harder, more complex and more thought-provoking analysis of the situation.