Tremendous? A congressman even apologized to BP for people saying they were unhappy with the company, and the company's fines had both no effect on their business and did not compensate for even the economic loss of the people in the area.
There were pension liquidity fears at the time due to the costs that it needed to pay. BP provides a large percentage of dividend payments on the the London Stock Exchange which pension funds rely on for paying out pensions.
The wikipedia page is quite clear on how much BP paid in damages and they were not insignificant - $42Billion had been paid into a trust fund.
To say no effect is incorrect.
I worked in Houston just after the spill and heard BP was in shambles at the time.
Weren't there some $63B in cleanup efforts?