This Week in Markets: Friday 21 August 2026

Covering trading sessions: Tuesday 18, Wednesday 19 and Thursday 20 August 2026

Preheader: A memory-chip selloff hit Wall Street, the US Treasury doubled down on bond buybacks to calm yields, the relief lasted one session, and the ASX's flat headline number hid CSL jumping 17% on a first-ever annual loss.

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Dear Investor,

The US Treasury tried to fix the bond market this week, and the fix lasted about a day. Tuesday opened with a proper tech wreck: the Philadelphia Semiconductor Index fell 5.4% and briefly pushed the Nasdaq-100 into correction territory, as IDC warned global smartphone volumes are on track for their steepest annual decline on record, a "tsunami-like shock" it traced back to the memory chip supply chain. SanDisk, Western Digital and Micron all copped it. Then, on Wednesday, Treasury Secretary Scott Bessent announced his department would more than double its buybacks of long-dated government debt, at least US$4 billion per operation from 9 September, an unusually direct intervention aimed at yields that had pushed the 30-year Treasury to a 19-year high above 5.33% the previous week. It worked, for a session. The 10-year fell to 4.647%, the 30-year tumbled 9 basis points to 5.196%, and stocks edged higher. By Thursday the relief had gone: yields rebounded, President Trump vowed to squeeze Iran's economy after the US-Iran memorandum of understanding lapsed without renewal, oil jumped on the threat, and Walmart sank as much as 9.7% on weak sales guidance and dragged the Dow down with it.

The ASX told its own version of the same story: a headline number that gave away almost nothing. The index closed the three sessions up just 13.8 points (0.15%), which sounds like a market doing very little. Underneath it, CSL jumped 17.3% on the day it reported its first-ever statutory annual loss, BHP and Pro Medicus both delivered clean beats, the big four banks fell on soft home-lending data, and Thursday's weaker-than-expected jobs report (unemployment up to 4.5%, the highest since late 2021) killed off any remaining chance of a September RBA hike and sent gold miners up as much as 10% at the open. Reporting season, not the index level, is where this week actually happened.

In a sentence: A chip selloff, a Treasury-engineered bond rally, and the bond rally's failure all landed inside three trading sessions, while the ASX's near-flat headline concealed CSL surging 17% on a loss and a jobs report that ended any near-term case for an RBA hike.

01. US Markets & Macro

Tuesday's session was a straightforward risk-off move in one sector. The S&P 500 fell 0.69% to 7,691.76, the Nasdaq Composite dropped 1.33% to 26,289.71 and the Dow slipped a comparatively modest 0.22% to 53,343.40, as the Philadelphia Semiconductor Index shed 5.4%, on pace to wipe out several hundred billion dollars of sector value. IDC's warning that 2026 global smartphone volumes will fall around 13%, their steepest year-on-year decline on record, gave the memory-chip weakness a demand-side story to attach to, not just a valuation one. Rising long-end Treasury yields, sitting near their highest since 2007, added a second headwind to every long-duration tech name in the index.

Wednesday belonged to the bond market. Bessent's Treasury said it would more than double long-dated debt buybacks to at least US$4 billion per operation starting 9 September, an intervention JPMorgan analysts later described as doing little to fix the "unsustainable fiscal deficits and rising inflation expectations" actually driving yields higher, but the market took the immediate signal anyway. The 10-year Treasury yield fell to 4.647%, the 30-year dropped 9 basis points to 5.196%, down from a 19-year high above 5.33% the week before. Equities responded in kind but without much conviction: the S&P 500 rose 0.21% to 7,707.98, the Nasdaq added 0.16% to 26,331.09 and the Dow gained 0.22% to 53,463.05, with health care and cyclicals doing the work while tech stayed soft.

Thursday undid most of it. Yields rebounded as traders concluded the buyback boost was a liquidity plaster, not a fix for the deficit and inflation dynamics behind the move, and Trump's pledge to economically "crush" Iran after the US-Iran memorandum of understanding lapsed sent oil higher on renewed supply-risk pricing. The Dow fell as much as 380 points (0.71%) to around 53,083, though wire reports differed on the session's exact low, with some putting the intraday fall closer to 700 points. The S&P 500 slipped to around 7,655, down roughly 0.7 to 0.8%, with the Nasdaq off close to 1%. Walmart did its own damage on top of the macro story, sinking as much as 9.7% on disappointing sales guidance, one of its worst sessions in years.

02. Australian Market Performance

Tuesday was reporting season in its purest form: an index that barely moved and individual stocks that moved a great deal. The ASX 200 closed at 9,070.0, down just 3.2 points (0.04%), falling agonisingly short of snapping a five-session losing streak. Health care was the standout sector, up 8.1%, carried by CSL, Pro Medicus and Cochlear. CSL (CSL +17.34% to $157.94) hit a six-month high despite booking a first-ever statutory annual loss of US$2.58 billion, a non-cash writedown the market looked straight through in favour of FY27 guidance for the Behring plasma business to return to mid-single-digit revenue growth. Pro Medicus (PME +8.72% to $191.22) delivered revenue up 23% to $261.7 million, underlying EBIT up 24% and ten new imaging-software contracts worth more than $407 million. BHP (BHP +3.1% to $64.12) reported FY26 revenue up 15% to US$58.8 billion and underlying EBITDA up 27% to roughly US$33 billion on record WAIO iron ore volumes. None of it was enough to lift the index, because banks and retail dragged the other way in equal measure.

Wednesday was the banks' turn to disappoint. The index held near flat at 9,070, halting the losing streak, but the big four fell 0.6% to 2.3% on soft home-lending figures tied to May's tax changes, with CBA (CBA -1.18% to $160.71) and NAB (NAB -0.71% to $38.92) among the weakest. Bargain-hunting elsewhere in the market offset the drag, helped by an improvement in August consumer confidence.

Thursday brought the week's clearest macro catalyst. The ASX 200 rose 0.3% to 9,083.80 after the ABS's July labour force report showed unemployment climbing to 4.5% (from 4.4%, above the 4.4% consensus), the highest since late 2021, with employment down 15,800 (full-time up 16,300, part-time down 32,200) and the participation rate down 0.2 percentage points to 66.9%. Economists moved swiftly to price out any chance of a September RBA hike. Gold miners opened as much as 8 to 10% higher on an overnight bullion surge, and materials, health care and tech carried the index while banks, industrials and telcos stayed weak. Zip Co (ZIP +18.4%), Super Retail Group (SUL +14.9%) and Codan (CDA +12.4%) led the gainers; Downer EDI (DOW -10.1%), Sonic Healthcare (SHL -9.5%) and Medibank (MPL -8.2%) led the laggards. Net across the three sessions: 9,070.0 to 9,083.80, up 13.8 points (0.15%), a headline that undersells just how much moved beneath it.

03. Commodities & Currency

Gold was the week's clearest winner. It traded around US$4,394 on Tuesday, held a wide US$4,368 to US$4,480 range through Wednesday as it strengthened into the FOMC minutes release, then surged roughly 4% overnight into Thursday, the move that opened Australian gold miners up double digits at the bell. Iron ore was comparatively sedate: the Dalian futures contract settled at RMB712 a tonne (+0.78%) on Wednesday, spot prices at Qingdao eased RMB2 to 3, and blast-furnace utilisation across 242 sample Chinese mills sat at 88.84%, consistent with steady mill demand rather than a restocking rush.

Brent crude climbed through the week on the same Hormuz dynamic driving oil higher globally: US$92.42 on Tuesday, above US$92 on Wednesday, and US$93.01 (+1.52%) on Thursday, up more than 4% for the week as Trump's threat to squeeze Iran economically revived supply-risk pricing rather than resolving it. The AUD/USD held a 0.7060 to 0.7123 range across the week, printing 0.7123 by Thursday morning, supported by broad greenback softness even as risk appetite swung on the Hormuz and Treasury-buyback headlines.

04. Reporting Season & Stock Highlights

The two most interesting reactions this week were both about what investors chose to ignore. CSL booked its first-ever statutory annual loss, US$2.58 billion, and the stock still rose 17.3% in a single session because the market was pricing the FY27 guide, Behring returning to mid-single-digit revenue growth, and treating the writedown as a one-off rather than a read on the business. Northern Star Resources went the other way: an unambiguous beat, underlying EBITDA up 22% to A$4.3 billion, underlying NPAT up 26% to A$1.8 billion on revenue up 19% to A$7.6 billion, and return on capital employed up to 13.4%, and the stock still needed Thursday's gold price surge to properly participate in a rally. A clean result and a clean loss can produce the same share-price direction if the market has already decided which number it's paying for.

BHP and Pro Medicus rounded out a strong Tuesday for anyone that actually reported. BHP's FY26 net profit rose 9% to US$9.8 billion on record WAIO iron ore volumes and roughly 2 million tonnes of copper for a second straight year, with a final dividend of US99 cents taking the full-year payout to US$1.72 a share; shares rose 3.1% to $64.12. Pro Medicus lifted its full-year dividend 25% to 69 cents a share on ten new imaging-software contracts worth more than $407 million and underlying NPAT up more than 24%; shares rose 8.7% to $191.22. With BHP, CSL, Pro Medicus and Northern Star all now through, reporting season's most closely watched names have delivered, and the dispersion between them, one loss rewarded, one beat needing an outside catalyst, is the more useful signal than the index's flat three-session move.

05. Geopolitics & Trade

The 60-day US-Iran memorandum of understanding, signed in June to hold a ceasefire, reopen the Strait of Hormuz and have Iran reaffirm it isn't pursuing nuclear weapons in exchange for the US lifting its naval blockade, lapsed on 17 August with no extension agreed. Through this week's coverage window, Iran and Oman kept working a separate bilateral framework for shipping through the strait, reportedly close to but not yet finalised, with Iran managing inbound traffic on its side of the channel and Oman managing outbound traffic on its own side.

Trump's public position hardened as the week went on, from threatening to bomb Oman if it "gets in the way" of a deal, to vowing by Thursday to squeeze Iran's economy directly. Oil moved higher each time the rhetoric escalated, Brent up more than 4% for the week, and each escalation has, so far, moved the price a little less than the one before it. We would read that as the market pricing this as a persistent tax on oil rather than a fresh crisis, not as the risk fading.

06. What We're Watching

Reporting season winds toward its final weeks, and the RBA's next move, or lack of one, is now the clearer story than it was a fortnight ago: Thursday's jobs report has pushed September hike odds to near zero. On the US side, we're watching whether the Treasury's doubled buyback programme, effective 9 September, provides more durable relief once it's actually running, or whether Thursday's fast reversal is the better guide to how markets will treat it. The Hormuz standoff remains unresolved and is still the swing factor for oil, gold and risk sentiment heading into next week.

Positioning takeaway: With the RBA's case for a September hike gone the same week the US Treasury's own bond-market intervention lost its grip inside a day, we're reading both as signals that growth is cooling faster than inflation on both sides of the Pacific, not as noise to look through. Gold did more for a portfolio this week than either bond market's engineering or the ASX 200's headline number. We would rather hold businesses the market rewards for being honest about a bad number, as it did with CSL's writedown, than ones still guiding to numbers the market hasn't yet chosen to believe. Past performance is not a reliable indicator of future performance.

Sources

• US index closes 18 August 2026 and semiconductor selloff: Yahoo Finance "Stock market today: Dow, S&P 500, Nasdaq fall as chip stocks sell off, bond yields rattle markets"; Detroit News "Tech selloff pulls Wall Street to two-week lows, oil and yields climb"; NBC News "Nasdaq-100 slides into correction as global chip and memory stocks sell off"
• Treasury buyback announcement and 19 August market reaction: CNBC "Treasury doubles debt buybacks as Bessent moves to steady bond market"; Bloomberg "Bessent's Treasury Buyback Expansion Spurs Drop in 30-Year Bond Yields"; Investing.com/Reuters "US Treasury buyback limits bond market pain, but relief may be brief"
• US index closes 20 August 2026 and Walmart: Bloomberg "US Stock Futures Fall as Oil, Yields Climb While Walmart Slumps"; Yahoo Finance "Stock market today: Dow, S&P 500, Nasdaq slide as bond relief evaporates, Walmart stock takes a hit"; CNBC "Treasury bond buybacks ease long-term yields, but analysts see limited relief"
• ASX 200 close and reporting season 18 August 2026: ABC News "ASX falls short of snapping five-day losing streak after bumper earnings results for BHP, CSL and Pro Medicus"; Stockhead "Closing Bell: CSL explodes, BHP booms, ASX has a lie down"; Motley Fool "Why is everyone talking about CSL, Pro Medicus and BHP shares on Tuesday?"
• ASX 200 close 19 August 2026 and bank weakness: ts2.tech "ASX 200 Steady at Close After Volatile Earnings Shifts Ahead of Wage Report"
• ASX 200 close and jobs report 20 August 2026: ts2.tech "S&P/ASX 200 Rises 0.3% After Weaker Jobs Ease Rate Fears; Gold, Tech Outperform"; ABC News "Unemployment rate hits 4.5pc, the highest level in post-COVID era"; Australian Bureau of Statistics "Unemployment rate rises to 4.5% in July"
• BHP and CSL FY26 results: BHP "Results for the full year ended 30 June 2026"; Stockhead "Lunch Wrap: CSL erupts as BHP showers investors with copper cash"
• Northern Star Resources FY26 results: Investing.com "Northern Star FY26 slides: EBITDA surges 22% amid peak investment"; Kalkine "Northern Star Resources Reports FY26 Annual Results"
• Gold, Brent and iron ore prices: CNBC "The price of gold today, August 19, 2026"; Yahoo Finance "Gold prices today, Wednesday, August 19, 2026"; Centrino Capital market data note, 18 August 2026; Hellenic Shipping News "MMI Daily Iron Ore Index Report August 19 2026"
• Strait of Hormuz and Iran-Oman talks: CNN "August 18, 2026 - Trump says no talks underway with Iran"; CBS News "Iran, Oman deal on Strait of Hormuz getting close, Tehran says"; NBC News "Trump threatens to bomb Oman if it 'gets in the way' of Strait of Hormuz talks with Iran"

Preflight

Notes

• Automated scheduled run (twice-weekly-market-update-friday), no human present. Research conducted entirely via WebSearch against public sources; Marcus Today was not scanned as this environment has no saved Marcus Today login reachable from a non-interactive session.
• Thursday 20 August's exact US index closes carried conflicting figures across wire summaries (Dow decline reported variously as 0.71% and as "nearly 700 points"/1.3%). Rather than present a single unverified precise number as fact, the draft states the more consistently sourced 0.71%/~380 point figure and explicitly flags the wider range reported elsewhere, consistent with this workflow's rule against presenting AI-derived or uncertain figures as reported fact.
• Gold's precise Thursday 20 August US close was not confirmed from available sources; the draft describes the move as "roughly 4%" overnight, sourced to the ASX gold-miner reaction it produced, rather than quoting an unconfirmed dollar figure.
• BHP's underlying EBITDA is cited as "roughly US$33 billion" reflecting a minor variance between sources (US$32.9bn per one wire, ~US$33bn per BHP's own release); the rounder figure is used with the precise wire figure available in the briefings file if needed.