Greece's banks are crashing again

Another day, another almost unbelievable roller coaster ride for Greece's fragile banks. The biggest four are all down between 8.8% and 15% as of 10:35 a.m. GMT.

The banks plunged when Syriza was elected, losing about 40% of their share value in three days (and half for some individual banks). They then climbed back and slumped again, following the turbulent early negotiations for a deal on Greek debt.

Today, it's downwards again. Here's how Piraeus Bank's last few weeks look:

New Prime Minister Alexis Tsipras gave his first major speech Sunday evening, and this is the aftermath. Tsipras signalled absolutely no concessions, indicated that the Greek government would definitely not apply for an extension of the country's bailout, and generally raised the stakes.

The Economist Intelligence Unit has increased its chance of a Greek exit from the eurozone from 30% to 40%, and banks are clearly not appreciating that extra risk.