The Australian sharemarket suffered its worst week since August as investors booked profits ahead of a widely expected interest rate cut by the Federal Reserve at its last policy meeting of the year.

The S&P/ASX 200 ended the session 0.4 per cent lower, or 34.3 points, to 8296, the lowest level in four weeks. The index fell 1.5 on the week, the largest decline since early August. The All Ordinaries also lost 0.4 per cent.

Of the 11 sectors, nine retreated, with sharp losses in miners as Beijing’s pledge to boost its economy failed to lift investor sentiment. Iron ore prices traded in Singapore slumped 2.4 per cent to below $US104.

BHP Group lost 1.5 per cent to $41.17. Rio Tinto tumbled 2.8 per cent to $120.72, also weighed by news it had committed $US2.5 billion to expand its lithium project in Argentina. Fortescue skidded 3.7 per cent to $19.48, further undermined by a downgrade to hold by broker Morgans due to governance concerns.

Gold miners also suffered deep losses with St Barbara down more than 7 per cent despite higher prices of bullion.

Software provider Iress was among the top gainers, leaping 8.2 per cent to $9.38 after it reaffirmed earnings guidance of $126 million to $132 million for fiscal year 2024 and announced the reinstatement of dividends.

Financial services giant Insignia Financial jumped 6.2 per cent to $3.61 per cent after it received a takeover bid from Bain Capital at $4 per share. Shares climbed to an intraday high of $3.725, a peak last seen three years ago.

Data centre landlord DigiCo Infrastructure REIT had a lacklustre start on the ASX. It closed at $4.55 in its first session on the market, down from an initial public offering of $5. Meanwhile, DigiCo parent, HMC Capital, led by dealmaker David di Pilla, was the biggest laggard on the index, down 7.2 per cent to $11.26.

In other corporate news, insurer Steadfast Group slipped 0.5 per cent to $5.77 after it emerged two employees are under investigation for insider trading.

In commodities, Resolute Mining retreated 1.2 per cent to 43¢ after chief executive Terry Holohan announced he was taking a leave of absence until late January.

And, South32 swung to a 1.2 per cent loss to $3.4 despite receiving the backing of Western Australia’s environment minister to extend the life of its Worsley Alumina project, trumping concerns from the state’s environmental watchdog.