Don't get too excited about oil's $50 milestone Thursday. While both Brent and West Texas Intermediate crossed $50 a barrel, next week's OPEC meeting could break the rally.

"Iran is determined to ramp up productions to its pre-sanction levels," says Jasper Lawler, a markets strategist with CMC Markets, adding that Saudi Arabia won't agree to a production freeze unless Iran participates.

"I think we can expect [no production freeze] from this meeting and the result from the past three meetings has been a big dive in oil prices."

During OPEC's previous meeting back on April 17, no production deal was reached amid tensions between Iran and Saudi Arabia. Iran officials didn't attend April's meeting.

Lawler says if prices don't nosedive following the June 2 OPEC meeting, that would represent a turning point for the closely watched commodity.

West Texas Intermediate is up 21% since the start of the year.

"[$50 oil] is a level that a lot of shale producers and some of the big oil companies have referenced as being a turning point," Lawler says, adding that shale companies now have an incentive to ramp up production now that oil is at $50. "We've seen U.S. production slow over the last four months and the risk here is that these higher prices trigger an extra bit of U.S. supply and that could push prices down." 

Oil and stocks continue to move in a lockstep pattern, with the three major U.S. stock indexes rising over the past few sessions amid gains in oil. Lawler said the rally in stocks is largely amid profit taking.

Aside from oil, Lawler says the markets are also on-edge over the Federal Reserve's June meeting. Fed officials have been hinting at a June rate hike in recent weeks.

Fed Chair Janet Yellen is set to speak at Harvard University on Friday and investors will be looking for any hints on the timing of the central bank's next move.