Howard Marks' Lesson for Wartime Markets: Brent Above $91 and the UAE's Break With Iran, Explained for Tehran's Bourse (Wednesday, August 19, 2026)

1. Lead

Howard Marks has an important lesson for the stock market in wartime: you can't predict the future, but you can prepare for it.

On Wednesday, August 19, 2026 (28 Mordad 1405 in the Iranian calendar), the United Arab Emirates suspended all trade and financial ties with Iran until further notice, hours after its defense ministry claimed it intercepted two Iranian ballistic missiles near Dubai, a claim Tehran immediately denied. At the same time, Brent crude pushed past $91 a barrel and world gold set a fresh record above $4,355 an ounce, both signaling risk aversion in global markets. Tehran's own benchmark, TEDPIX, shrugged off the headlines: it sits in the 5,952,000-point range today and is up nearly 7% over the past ten trading sessions. For an investor sitting at the Tehran bourse's screen today, the real question isn't "what happens with the war tomorrow" but "how prepared am I for each version of tomorrow."

2. Background

The current crisis is not new. The Islamabad ceasefire memorandum, reached in mid-July, effectively collapsed by Thursday, July 16, 2026, and the United States resumed its naval blockade of Iranian ports; the free-market dollar hit a record 188,000 tomans that same week. Since then, tension in the Strait of Hormuz has spiked repeatedly: the U.S. Treasury revoked authorization for dollar sales of Iranian oil after tanker attacks, the Houthis claimed a drone strike on Saudi Arabia's Jazan refinery, and on Saturday, August 15, 2026, for the first time on record, not a single tanker transited the Strait of Hormuz in a full day. Saudi Aramco resumed loading tankers from terminals inside the strait on Tuesday, August 18, 2026, after a three-week halt, but the UK Maritime Trade Operations agency simultaneously reported an unidentified projectile striking a tanker on the same route. The newest link in this chain is today's UAE decision to suspend trade and financial ties with Iran, a channel tied directly to the Tehran-to-Dubai dollar remittance corridor (hawala/havaleh, the informal transfer network much of Iran's import trade relies on).

Through this same stretch of tension, Tehran's bourse hasn't collapsed, it has kept setting records: TEDPIX climbed from 5,559,965 points on August 9 to 5,952,488 points today, August 19, a gain of nearly 7% in ten sessions. As BBC Persian reported, and Sahmino covered on August 14, 2026, Tehran's bourse, with the index up roughly 52%, has been Iran's best-performing asset market against 87.9% year-on-year inflation. That comparison shows Tehran equities have behaved differently from a raw flight from risk through the months of war, which is exactly the point Marks' lesson makes.

3. The market at a glance

The free-market dollar, which Sahmino's midday market pulse showed flat through 11 a.m. against yesterday evening's 187,010 tomans, moved as expected by 15:29 to 189,185 tomans, exactly the delayed remittance-market reaction to the UAE's decision that report said to watch for this afternoon.

4. Transmission channels into Tehran's bourse

The war and the Strait of Hormuz tension reach Tehran's trading floor through several specific channels:

• Exchange rate: the free-market dollar rose 1.16% today; a higher dollar lifts the rial value of export-oriented listed companies' revenue, but also raises the cost of imported raw materials.
• Oil and energy: Brent above $91 keeps global energy costs elevated; for Tehran's petrochemical and refining names, which price off the free-market dollar, more expensive oil can widen margins rather than threaten them.
• Inflation: the U.S. Federal Reserve's July 29 statement explicitly said energy supply shocks have kept inflation elevated "in certain sectors, including energy"; in Iran, that same pressure lands directly on industrial firms' production costs.
• Liquidity and investor behavior: retail trading flow on Tehran's main board was mixed over the past ten sessions (August 9 to 19): net selling on days like August 9 and 15, net buying on days like August 16 and 17. Sahmino's own recorded data shows no mass, panic-driven exit from equities in reaction to war headlines.
• Exports and company revenue: steel and petrochemical exports sit under the shadow of the same Hormuz shipping restrictions; Mobarakeh Steel (نماد فولاد) is the clearest example, reopening on Monday, August 17, 2026 after a five-month halt and rising 2.99% that day, yet still trading about 8.1% below its pre-halt price.
• Rate expectations: the Fed held its rate at 3.50% to 3.75% on a 9-3 vote at its July 29 meeting; all three dissenters wanted to raise rates, not cut them. That means, contrary to the popular reading in the gold market, the Fed's September meeting could bring pressure to hike rather than cut, a scenario that would strengthen the dollar globally and indirectly raise the cost of Iran's imports.

5. Three scenarios ahead, not a forecast

In keeping with Marks' logic, none of the three scenarios below is certain; the point isn't to predict which one happens, but to track the variables that will shape Tehran's bourse in the weeks ahead.

Scenario one, de-escalation: if the missile-interception claim near Dubai does not escalate militarily and the UAE restores ties in the coming days, Brent would be expected to retreat from the $91 range and the geopolitical risk premium to ease out of world gold and Tehran's free-market dollar. Variables to watch: a full return of tanker traffic through the Strait of Hormuz, and an end to fresh UK Maritime Trade Operations warnings.

Scenario two, the status quo continues: if tension stays at its current "threat without direct engagement" level, as it has for recent weeks, Tehran's bourse would likely continue its current pattern: a stepped rise in the main index alongside daily dollar and gold volatility, without one large single shock. The key variable here is how exchange houses and the Tehran-Dubai remittance corridor react to today's UAE decision in this evening's and tomorrow's trading.

Scenario three, escalation: if the Strait of Hormuz is effectively blocked or a new direct attack occurs, Brent could move quickly above current levels and inflationary pressure from the energy channel would reach regional economies; the cost of that can already be seen in Saudi Arabia's economy contracting 4.8% year-on-year this spring, driven mainly by a 24.7% drop in its oil sector. In this scenario, the Fed's behavior matters too: if an energy shock pushes U.S. inflation higher, the Fed's September meeting could tilt toward a hike rather than a cut, a move that would strengthen the dollar globally and add further pressure on Iran's exchange rate.

6. Howard Marks' lesson

The line "you can't predict the future, but you can prepare for it" is not a promise to call the market; it is, rather, an admission that no one, not the analyst and not the professional investor, knows whether tomorrow's war will be short or long. What is within an investor's control is the quality of their preparation for all three paths above, not guessing which one is correct. This is exactly where the difference between a short-term price reaction (like today's dollar and gold moves) and a genuine change in a company's fundamental value matters: a stock's price can swing several percent on a headline day without the company's actual profitability changing at all.

The biggest mistake investors make in high-tension periods is usually an emotional decision: selling everything at the peak of fear, or buying everything at the peak of excitement over one positive headline. A few practical, non-prescriptive principles apply here: first, stress-test your portfolio against all three scenarios above, not just the one you believe in. Second, distinguish between news that moves a price for a day and news that changes a company's fundamentals. Third, avoid making large decisions in the market's most emotional hours. None of this is advice to buy or sell; it is a framework for calmer decisions in the middle of uncertainty.

7. Bottom line

Today, August 19, 2026, Tehran's bourse displayed two contradictory realities at once: a heavy geopolitical headline (the UAE's break with Iran) and a main index up nearly 7% over ten days. That apparent contradiction is exactly what Howard Marks' lesson points to: markets don't always move logically in lockstep with the news cycle. What matters for a Sahmino investor isn't guessing how the war ends, it's testing their own portfolio against all three scenarios above.

8. What to watch

• How exchange houses and the Tehran-Dubai dollar remittance corridor react to the UAE's break in ties, in this evening's and tomorrow's trading
• Tanker traffic through the Strait of Hormuz following Aramco's resumed loading
• The Fed's next FOMC meeting in September, and whether the vote tilts toward a hike or holding steady
• Whether Tehran's main board keeps its net retail-buying trend or reverses it
• Follow the Sahmino calendar for the full schedule of capital-market events