Ouch – the BP (LSE: BP) share price has just fallen again. It’s today’s biggest FTSE 100 faller, plunging almost 5% this morning, on a day when most of the index got off to a flying start.

Commodity stocks such as Anglo American and Glencore are racing out of the traps as investors celebrate more Chinese stimulus, but BP shares are heading backwards. So is the Shell share price. It’s today’s second biggest faller.

That’s a blow for me because only a week ago I declared BP to be the bargain of the millennium. I put my money where my mouth is, and bought it a few days later.

Needless to say, I haven’t done well. So what’s up?

The oil price is under pressure

Saudi Arabia has apparently given up on attempts to drive the oil price back up to $100 a barrel, and is ramping up production to protect market share. This is a tacit admission that its longstanding post-war role has changed. Saudi is no longer the global swing producer. That crown now belongs to the US, thanks to shale. It’s a huge strategic shift.

It’s not the end of the world for BP. Brent crude is still above $72 a barrel, while it can break even with oil at $40 or possibly even $30. I can console myself with the dividends I’ll be getting, as BP now has a bumper trailing yield of 5.87%.

I’m curious about one thing, though. One of the biggest worries about investing in BP, or any energy giant, is that the world is supposedly racing to end its dependency on fossil fuels.

BP could fall even further

BP has struggled to keep pace with the energy transition leaving it vulnerable as renewables take over. Yet here we are, and BP is struggling because the world is pumping more and more oil, rather than less.

Investors like me have to ignore big macro factors like that. A few years ago, BP was supposed to fall because of the ‘peak oil’ scare. Instead of running out, we’re swimming in the stuff. Yet BP is struggling. Who knew that would happen? I didn’t.

I’ll stick to what I do know. BP has a long and proud track record. Its shares are down 25% in a year. They trade at just 6.06 times earnings, a fraction of the FTSE 100 average P/E of 15.4 times. The energy sector is famously cyclical. Best to buy when shares are down. This looks like an opportunity to me.

Brokers following BP have set an average one-year price target of 523.8p, up 36.23% from today’s 382p. Frankly, its shares could go anywhere. I could easily see it ending the year below 350p but the world still runs on oil and one day, BP will bounce back. I’m aiming to buy more of its shares before it does.