The Russian ruble is tumbling.

The petro-currency is down by 1.0% at 58.1678 per dollar as of 8:06 a.m. ET.

Earlier, data showed that Russian PPI rose by 12.7% year-over-year in January, marking the highest inflation since November 2015. It followed the 7.4% increase in December.

Moreover, Brent crude oil prices, which are down by 0.5% at $55.38 per barrel.

Although the ruble is down on Friday, the currency has strengthened in February, which has rattled folks in the Ministry of Finance, and has even drawn the attention of the Kremlin.

And, notably, there are a couple of unusual things about the currency's recent appreciation: first, the ruble has somewhat disconnected from oil prices, and second, it's not entirely clear what has been driving the rally.

As for the rest of the world, here's the scoreboard as of 8:16 a.m. ET:

    The British pound is down by 0.5% at 1.2426 against the dollar after UK retail sales missed big. Retail sales rose by 1.5% year-over-year in January, which was below the projected 3.4% increase. Separately, the number of European Union workers in the UK fell by 50,000 to 2.3 million in the fourth quarter, markin the largest drop in five years, according to the Office for National Statistics. The euro is down by 0.2% at 1.0650 against the dollar. In other euro news, Eurozone countries look like they might miss a self-imposed deadline next Monday to agree on aid measures for Greece, which might run out of money in July. The US dollar index is up by 0.2% at 100.63 on quiet data day. The Baker Hughes rig count will be released at 1 p.m. ET.