Take Five: World markets themes for the week ahead
Offshore oil platforms are seen at the Bouri Oil Field off the coast of Libya August 3, 2015. REUTERS/Darrin Zammit Lupi · Reuters

LONDON (Reuters) - Following are five big themes likely to dominate the thinking of investors and traders in the coming week, and the Reuters stories related to them.

1/OIL AT $80

Brent oil hit $80 a barrel this week - good news for exporters like Saudi Arabia and Russia but less so for importers such as India and especially those with big current account deficits, like Turkey. The loss of Iranian supply into an already tight market should keep prices elevated for now.

But $80 has proved a formidable psychological and technical barrier, so staying above that is going to be tricky. Brent briefly popped above $80 in May, marking its highest in over three years, but it could not maintain altitude. There's likely to be a lot of options positions around this big number, and for all you chartists out there, technicals are at play too. The 61.8 percent Fibonacci retracement of Brent's $90 plunge between June 2014 and January 2016, comes in just above $81.

There's another barrier to consider: Donald Trump. The U.S. president has complained repeatedly about oil prices, demanding OPEC action to bring them down. And he was doing that when oil was lower than it is today, so another tweetstorm from the White House would be a surprise to pretty much nobody.

GRAPHIC: Brent crude at $80 - https://reut.rs/2CSp9tb

2/BIT OF A STRETCH

When the Bank of Japan meets next week, it will scrutinize market moves since its July decision to allow bond yields more flexibility around its zero percent target. There won't be much to look at, though.

Despite Governor Haruhiko Kuroda's assurance the BOJ will allow 10-year yields to stretch to around 0.2 percent, they have been caught in a tight range around 0.1 percent. It's proving difficult to revive a market that has seen liquidity dry up as a result of the central bank's huge purchases. This in turn means strains on the banking sector will remain in focus. For now, the BOJ may blame sticky yields on a summer lull and prefer to wait for longer before drawing any conclusions. But policymakers will also have to debate the risks that global trade frictions pose to the export-reliant economy. They'll notice there was no holiday lull in the rest of the world.

GRAPHIC: BOJ struggling to make JGB markets more lively - https://reut.rs/2p6Gwwz

3/HOLD ON TIGHT

Turkey may have delivered a chunky 625 basis-point interest rate rise but similar fireworks are unlikely at next week's crop of central bank meetings in emerging markets. Nevertheless, with inflation and growth worries rising across the developing world and policymakers engaged in a delicate balancing act to calm investors, markets will watch for the sort of signals central bankers send.