The Australian sharemarket ended the first session of the week slightly lower, with the losses led by travel stocks and companies under the AUSTRAC microscope.

The S&P/ASX 200 Index fell 13.5 points, or 0.2 per cent, to 7281.9, hitting a record intraday high of 7309.4 earlier in the session.

AUSTRAC investigations hit a number of stocks. SkyCity Entertainment fell 6.5 per cent to $3.18, NAB dipped 3.2 per cent to $26.64, Crown slid 1.5 per cent to $12.50 and Star Entertainment Group declined 2 per cent to $3.89.

Travel stocks were also hit hard. Corporate Travel Management slid 5.1 per cent to $20.86, Webjet dipped 4.9 per cent to $5.04 and Flight Centre fell 4.8 per cent to $15.21.

Altium soared 39 per cent to $37.83 after it rejected a takeover offer from AutoDesk.

Nuix added 6.2 per cent to $2.75, Appen firmed 6.1 per cent to $12.99 and EML Payments advanced 4.2 per cent to $3.48.