Another record-breaking day for Afterpay lifted the Australian sharemarket to a third straight day of gains, but it wasn't enough to stop the index falling 0.6 per cent over the week.

The S&P/ASX200 Index rose 0.05 of a point to 6715.4 points on Friday after US President-elect Joe Biden outlined his $US1.9 trillion stimulus plan.

Afterpay was the star of the show as the buy now, pay later giant stormed 10 per cent higher to end at a record high of $133.15 on Friday, leaping over Telstra to become the 13th largest company on the ASX.

The stock rallied 14.8 per cent over the week after US-based rival Affirm almost doubled on its first day of trading in New York earlier in the week and Morgan Stanley lifted its share price target to $136 from $120.

Afterpay was the second-best performer in the S&P/ASX 200 Index over the week.

Other BNPL stocks also rallied on Friday. Sezzle rose 10.6 per cent to notch up a weekly gain of 19.8 per cent.

Tyro fell 11.8 per cent after short-seller Viceroy Research said the payments company's terminal outages are far more widespread than it is willing to admit. The stock was halted and management will respond to what it claims are "false allegations" next week.

Pro Medicus added 4.5 per cent on Friday, leaving the stock up 17.1 per cent for the week - and the best performer on the S&P/ASX 200 Index - after it signed a seven-year, $40 million US deal on Thursday.

Mining and energy stocks lifted on the prospect of more stimulus for the world's largest economy. BHP rose 1.7 per cent to $46.82 after hitting a record intraday high of $47.54. Woodside added 0.6 per cent on Friday, closing at its highest level since March.

Polynovo was the worst performer among the top 200 stocks over the week. It fell 28 per cent after the company said demand for its skin regeneration technology had slowed in the second quarter as hospitals were filled with COVID-19 patients.