ASX 200 Sheds $50 Billion In Worst Session Since March As Oil Tops $101 A Barrel Amid Iran Fears Today

SYDNEY — Australian shares suffered their worst trading day since March on Thursday, with the benchmark S&P/ASX 200 index tumbling 136.4 points, or 1.53%, to 8,775.0 by early afternoon, wiping roughly $50 billion off the local market as surging oil prices and rising global bond yields rattled investor sentiment.

The index fell as much as 1.8% during the session to touch 8,751 points, sending the ASX 200 to its lowest level in two-and-a-half months, back to where it stood on July 2. The decline effectively erased all of the market's gains accumulated over the preceding 10 weeks, with every major sector trading lower for a stretch of the session, including energy stocks, which fell despite the very commodity price surge that had helped trigger the broader selloff.

Brent crude oil climbed to $101.60 a barrel during Thursday's session, according to Motley Fool Australia, as tensions between the United States and Iran continued escalating following the weekend's exchange of strikes involving oil tankers and warships. The rise in oil prices has added further pressure to already elevated inflation expectations, pushing global bond yields higher and complicating the outlook for interest rates across major economies.

The U.S. 10-year Treasury yield climbed to around 4.84% overnight, its highest level since 2023, while Australian bond yields moved higher in tandem. That shift in the rate outlook has been reflected directly in market pricing for the Reserve Bank of Australia's next policy decision, with traders now pricing in roughly a 70% probability of another RBA rate hike at its Sept. 29 meeting.

Mining stocks bore a significant share of Thursday's losses, with iron ore prices slipping back below $100 a tonne, adding company-specific pressure on top of the broader market weakness tied to oil and bond yields. According to Market Index, the ASX 200 dropped below its 200-day moving average during the session, a level that had been sitting around 8,816 points before markets opened Thursday, putting additional technical attention on the 8,800 level as a potential area of support heading into the coming sessions.

Despite the severity of Thursday's decline, some analysts cautioned against characterizing the move as a full-blown correction. According to Market Index, the ASX 200 remains slightly higher for 2026 overall even after Thursday's slide, though the index now sits roughly 5% below its August record high, a gap analysts said leaves room for continued short-term volatility depending on how oil prices, bond yields and upcoming U.S. inflation data evolve in the days ahead.

Thursday's rout extends a difficult run for the Australian market stretching back through the opening weeks of September, a month that has historically proven to be the worst on the calendar for Australian equities. According to Market Index's historical analysis, the ASX 200 has averaged a 0.42% decline in September since 1980, rising in only 54% of years, making it statistically the weakest month for average returns. Total returns data since 2001 paints an even bleaker picture, with September averaging a 0.65% decline and finishing higher in just 44% of years, the worst performance of any month on that measure as well.

That seasonal weakness has coincided this year with a broader convergence of bearish forces across global markets. Bond yields have pushed to multi-year or, in some cases, record highs, with the U.S. 2-year yield at 4.34%, near its highest level since February 2025, and the Australian 30-year yield reaching an all-time high of 5.65% since regular issuance began in 2016. At the same time, commodity prices have remained stubbornly elevated, with Brent crude now trading well above the $90 level that had already been considered high earlier in the month.

Market Index's analysis drew comparisons to prior historically difficult Septembers, noting parallels with 1990, when the fallout from Iraq's invasion of Kuwait sent oil prices surging more than 150% and pushed equities into an extended slide toward an October bottom, and 2001, when the Sept. 11 terrorist attacks shut down the New York Stock Exchange entirely for four sessions.

Thursday's session followed a similarly negative close Tuesday, when the ASX 200 slumped 90 points, or 1.0%, to close at 8,921, itself a six-week low at the time, with weakness spreading across retail trade, financial and technology stocks. That decline came after Dow futures tumbled overnight on the combination of surging oil prices and escalating trade tensions between the United States and Canada, further compounding the pressure already facing Australian equities from the unresolved Middle East conflict.

Not every stock on the ASX moved lower Thursday. Greatland Resources rose 1.1% and AMP Ltd. added 0.6%, according to Trading Economics, offering isolated pockets of resilience even as the broader index posted its steepest single-day decline since March. Separately, gold miner St Barbara's shares reportedly opened higher Thursday following the completion of a major asset sale agreement involving its Simberi and Tabar Islands operations, according to Market Index's live coverage, illustrating how company-specific corporate developments continued to drive individual stock performance even amid the broader market rout.

With oil prices continuing to climb amid the unresolved conflict between the United States and Iran, and bond yields pushing to levels not seen in years across both American and Australian markets, investors are likely to remain focused in the coming sessions on whether Thursday's steep decline marks a temporary, seasonally driven pullback or the beginning of a more sustained repricing of risk across Australian equities. Market participants will also be watching closely for any further developments in the Middle East, additional signals from the Reserve Bank ahead of its September policy decision, and upcoming U.S. inflation data that could further shape the direction of both bond yields and equity markets heading into the remainder of the month.