Our current crisis is a less Marxist one than almost any post-war recession.
To Marx, crises originated in the real economy. Recessions occur when an over-accumulation of real capital equipment combine with a lack of demand to cause a falling rate of profit and then capital-scrapping, job cuts and slump.
Now, this was a great explanation for previous recessions. The long boom of the 1950s and 60s led to over-accumulation and falling profits and the recessions of the 70s and 80s. The tech bubble of the late 90s caused a massive over-accumulation of capital and nugatory profits. It's this stress upon profits that elevates Marx and his follower such as Kalecki above mere Keynesians.
However, this is a poor description of our current woes. Non-financial profits have been reasonably healthy. Instead, this crisis originates in the financial system.
To Marx, however, finance was not so much a cause of capitalist crises - and for that matter of capitalist growth as well - but a mere accelerant of them. It’s the petrol, not the spark. Credit, he wrote (vol III, p572), “accelerates the violent outbreaks of this contradiction, crises…” Accelerate, note, not cause.
Of course, Marx took a dim view of those in the financial system. Finance, he wrote:
Nor did Marx say much about the mechanisms that caused waves of financial speculation and crashes. If you want such a theory, you’d better look to Minsky than Marx.
Of course, I’ve said that this crisis shows that the capitalist mode of ownership is dysfunctional. But I mean this in a different sense to Marx. I mean that individual companies are inefficient. But it’s not clear that Marx thought this. Instead, his big contribution was to show that capitalism was micro efficient but macro inefficient. He showed how individual capitalists, each pursuing profit maximization, could produce an outcome that was bad for capitalists in general - falling profits and crisis. He seems to have taken for granted that individual capitalist enterprises were rationally organized - though this could well have been a postulate for the sake of argument, rather than a direct claim.
So, Marx is not especially relevant to this crisis.
But this is not to say that Marx is irrelevant generally. Quite the opposite. On many things, Marx was right. He was right to show that capitalism was a force for great growth and great instability; right to show that profits arose from exploitation; right to stress that technical progress determines social conditions; right on alienation and primitive accumulation. And where he was wrong, for example in foreseeing the death of capitalism, it was because he was merely following his classical predecessors, among them Adam Smith.
So, Marx has much to tell us today - but not about the financial crisis.