Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Tesco (Nasdaq: TESO) jumped as much as 11% today as oil prices rose.

So what: Oil is up 4.3% as of this writing on concerns over Iran's threats to close the Strait of Hormuz and on economic hopes. A rising market has helped stocks, but investors are at least concerned that Iran will do something drastic.

Now what: The experts are saying that Iran is bluffing, and considering that closing the Strait of Hormuz would hurt China more than the U.S. I doubt Iran will do it. But Iran has been posturing for days now with no signs of backing down. In the meantime, oil keeps going up, pushing oil-related stocks along with it.

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