Oil prices tumbled on Wednesday and global stock markets rallied after the US and Iran agreed a two-week conditional ceasefire.

Investors welcomed the news that Donald Trump had held off on his threat to bomb Iran into “the stone ages”, while Iran’s foreign minister, Abbas Araghchi, said passage through the strait of Hormuz would be allowed for the next two weeks under the management of Iran’s military.

Oil fell below the $100 a barrel mark, even though it was not certain that the US would accept a 10-point proposal drawn up by Iran. How the strait will be reopened and managed beyond the two-week grace period is yet to be determined.

Brent crude oil, the international standard, dropped by 16%, while US crude oil futures sank by 17.6%. However, prices later recovered off their lows as Israel launched its biggest attacks yet on Lebanon and on reports that Iran halted the passage of oil tankers because of an alleged Israeli ceasefire breach. Reports of an attack on Saudi Arabia’s huge east-west pipeline to the Red Sea, which allowed oil exports to avoid the strait, also nudged prices higher.

Kathleen Brooks, a research director at the trading platform XTB, said markets would be monitoring the fragile truce. “Only if the US or Iran walk away from the ceasefire completely and bombing restarts do we see the oil price potentially surging back to the highs of this week above $110 per barrel for Brent crude, which could also cause stocks and bonds to slump,” she said.

By late Wednesday afternoon London time, Brent crude was down 13.5% at $94.36 a barrel. US crude was down 15.5% at $95.36 a barrel, heading for its biggest one-day fall since the Covid-19 lockdowns six years ago.

The prices remain well above where they were before the start of the Iran war, when Brent traded below $73 a barrel.

Reuters reported on Wednesday that investors placed a combined $950m bet on oil prices falling, hours before the ceasefire was announced.

With just over an hour until his deadline was due to pass on Tuesday, the US president said he was holding off on threatened attacks on Iran, subject to Tehran agreeing to a two-week ceasefire and reopening the strait of Hormuz.

Soon after, Iran’s national security council confirmed it had accepted a two-week ceasefire if attacks against Iran were halted. Tehran said peace negotiations with the US would begin in Islamabad on Friday.

European stock markets rallied strongly on Wednesday. The pan-European Stoxx 600 index gained 3.7%, its biggest one-day rise in a year. Travel and leisure stocks soared, with Air France gaining 13%, Lufthansa’s shares jumping by8%, the British Airways owner, IAG, up8%, and the holiday group Tui gaining almost 10%.

In London, the FTSE 100 index closed up 2.5% at 10,608.9 points, its highest end-of-day level since the early days of the Iran war. Oil company shares tumbled, though, with BP down 6% and Shell losing 4.7%.

The US stock markets jumped at the start of trading as Wall Street hailed the ceasefire. The Dow Jones industrial average gained almost 1,400 points, or 3%, in early trading, with travel company shares soaring but oil producers slumping.

That followed strong gains in Asia Pacific markets, where Japan’s benchmark Nikkei 225 gained more than 5%, Australia’s S&P/ASX 200 jumped 2.55% and South Korea’s Kospi soared by 7.5%. Hong Kong’s Hang Seng was up 3.1%, while China’s CSI 300 index gained 3.2%.

European gas prices slumped, with the month-ahead UK gas contract down 17% at 111.1p a therm on Wednesday afternoon.

Jim Reid, a markets strategist at Deutsche Bank, said: “Investors will be breathing a big sigh of relief that an off-ramp out of the war is being taken even as there’ll be various elements to watch to see whether this leads to sustained de-escalation.

“Will the ceasefire hold? We saw some strikes by Israel and Iran overnight, though these may have been in the works before the conditional ceasefire. We’ve also seen conflicting commentary on whether the ceasefire will extend to Israel’s action in Lebanon. Can talks lead to a permanent cessation of hostilities?”

In the bond market, treasury yields eased on word of a potential ceasefire. The yield (or interest rate) on the 10-year treasury fell to 4.24%, from 4.30% earlier on Tuesday. UK government bond prices strengthened, pushing down the yield on 10-year UK debt to 4.7%, down from 4.9% on Tuesday.

Gold prices rose more than 2% to $4,812 an ounce. Cryptocurrencies also rallied, with bitcoin advancing 2.9% to $71,327, and ether climbing 5.6% to $2,234.

Saul Kavonic, the head of energy research at MST Financial, said the two-week pause provided “an off-ramp for Trump’s overly bombastic ultimatum, but not yet an off-ramp for oil markets or the war”. He told Reuters it was unlikely oil and LNG production would resume until there was more confidence in a lasting ceasefire.

Kavonic said: “A two-week ceasefire would enable a release of some oil and LNG tankers from the strait of Hormuz to market, providing some market pressure relief in May. This does not result in more production, just a release of storage on water.”

For markets, the most critical issue remains the status of the strait of Hormuz, said Neil Shearing, the group chief economist at Capital Economics. He said: “The [10-point] framework appears to allow the full passage of oil tankers through the strait, but the terms under which this would occur remain unclear. Some reports suggest the introduction of transit fees of around $1-2m per tanker.

“Given that tankers typically carry 1-2m barrels of crude, such fees would add roughly $1 per barrel to the cost of oil transported through the strait. This would therefore have only a modest impact on global energy prices, though in practice it could amount to a de facto partial nationalisation of the shipping route.”

Prashant Newnaha, a senior strategist at the Singapore-based TD Securities, said a renewed escalation could not be ruled out “but markets are treating this ceasefire as the real deal and all parties involved will sell the ceasefire as a major win”.

He said: “Looking further out, oil prices are not returning to prewar levels. This will leave inflation persistence as a key theme for markets to ponder.”

With Associated Press