How extremely odd. Wonder why the values haven't converged? Do people inside the country not have access to this information? What's stopping someone from buying 150 rubles for a dollar and then buying $1.40ish for those same 150 rubles?

I should have perhaps mentioned in the original post:

1$ = 152,3₽ (buying 1 US dollar)

1$ = 85,7₽ (selling 1 US dollar).

Just because you pay 152₽ to buy 1$ doesn't mean you can sell it at the same price. At least banks won't buy it.

According to banki.ru the best price for selling US dollar now is 94,00₽.

Hope that clarifies it.

I see, the friction is in doing the reverse transaction. I guess you could find a buyer outside the traditional markets to complete the arbitrage transactions but that's going to be risky. Thanks for the clarification.

In times of such turmoil the spread between buy and sell price becomes so vast that it'll shield the exchangers from such schemes.