BP earns about $250bn a year, Lehman Bros rarely topped $3bn, and of course now are bust.
One was an investment bank, the other is an oil company. So why are we even comparing the two?
Well, there's just a chance, a tiny chance, that BP's current predicament could lead to Chapter 11 or worse. And you might think that all that would affect is the price of oil, until the other majors step into the market share and take up the slack.
Think again! All the big oil companies are major market players across the board. Obviously they play the oil futures market but they are so cash rich they trade all over the place, especially currency and foreign exchange. There was a time they subcontracted this work to merchant banks, but not these days. Nope, these days they have massive treasury operations departments entering into deals the size of which Lehman's could only ever have dreamt of.
BP has earnings 80 times what Lehman's ever had. Lehman's is generally held, in retrospect, to have been too big to have been allowed to fail. Imagine the systemic shock to the financial markets if BP should go bust.