The Australian sharemarket fell as weakness in banks and miners offset a big day of gains for Afterpay, with the buy now pay later (BNPL) juggernaut's share price electrified by a deal with Westpac.

The S&P/ASX200 Index fell 44.8 points, or 0.7 per cent, to 6184.6 points after Wall Street slipped on fading hopes for another round of stimulus and on concerns about the rising number of new COVID-19 cases.

Afterpay was the star of Tuesday's session, rising above $100 a share for the first time as a deal with Westpac will allow it to offer transaction and savings accounts to its 3 million-plus Australian customers as it makes a strategic shift towards banking.

Afterpay's 4.5 per cent advance lead the technology sector higher for a third straight day. The S&P/ASX All Technology Index added 1.1 per cent to a record 2721.5 points.

Rival BNPL provider Zip fell 1.4 per cent after it extended its 'shop anywhere' functionality into physical stores, announcing deals with Visa, Apple and Google on Tuesday. 

BHP was the biggest drag on the drag on the market, falling 1.6 per cent.

The world's largest miner signalled it won't be going ahead with its $US2.5 billion Olympic Dam Brownfield Expansion as the company's flagship iron ore division made a strong start to the new financial year.

BHP shipped 74 million tonnes of iron ore from Western Australia in the three months to September 30, including tonnes owned by joint venture partners, putting it on track to beat its full year target.

Among other blue chips, Commonwealth Bank fell 1.2 per cent and CSL dropped 1 per cent.

Cochlear added 2.3 per cent after reporting its revenue in the first quarter of the new financial year is still yet to catch up to where it was a year prior, with unit volumes falling, largely due to weakness in emerging markets. Cochlear implant revenue for the September quarter was 94 per cent of the same quarter in 2019 on a constant currency basis.

CIMIC fell 0.4 per cent after announcing it will write off a $1.15 billion contract asset for work performed by its subsidiary CPB Contractors on the Gorgon LNG jetty after the conclusion of a dispute with Chevron.

Stockland Group dropped 0.7 per cent after the property group said conditions have improved during the first quarter of the year, allowing for strong performance in its residential business and a strong rebound in its commercial business.

IDP Education 7.2 per cent after it used a trading up date to report its English language testing business had reached 70 per cent capacity.

Lovisa fell 0.3 per cent after reporting comparable store sales for the first 16 weeks of the 2020 financial year were down 10.2 per cent, an improvement on the 19 per cent fall through the first eight weeks.