Fear crippled many during last week’s market swoon. But Warren Buffett got greedy…

Business Insider reports the world’s second-richest man invested $4.5 billion in titan oil refiner Phillips 66 (NYSE: PSX).

He pounced on the market’s weakness to pile into his position.

Buffett now owns almost 58 million PSX shares. That’s about 10% of the company. The chart below shows how it happened.

Regular Daily readers know we emulate Buffett’s investment style at PBRG. His mantra is one of our all-time favorites:

Be fearful when others are greedy, and greedy when others are fearful.

As everyone else panicked, Buffett’s mantra led him to scoop up PSX shares at a near-10% discount.

But there’s a deeper lesson here… something most commentators miss.

Buffett’s most recent 13-F filing (an SEC regulatory disclosure) reveals he started buying PSX shares earlier in August—before the market’s drop.

And when shares cratered, Buffett didn’t panic… he bought more.

This move won’t surprise PBRG’s Legacy Portfolio subscribers. They know the secret to generating enormous wealth in the stock market is to buy relentless, dividend-raising, global powerhouse companies—like Phillips 66—anytime they present good valuations.

And when they present great valuations—like during last week’s market plunge—you “back up the truck” and buy more. Just like Buffett did.

(For more insight on the Buffett approach to investing, read our next item. It’s from the Legacy Portfolio’s chief analyst, Greg Wilson.)