Stocks to watch on the Australian stock exchange:

Australian shares have closed lower after sentiment was quelled by falls on overseas markets.

APN News and Media is hoping significant investment in outdoor advertisements can help them recover from a tough 2011.

Origin Energy has booked a substantial first half net profit and is considering the further sell-down of its stake in a big Qld LNG project.

BHP's decision to suspend work at its TEMCO facility in Tasmania may affect around 330 permanent staff.

Higher earnings from lotteries have helped gambling firm Tatts Group lift its net profit for the first half of the 2011/12 financial year by 11.3 per cent.

The Australian dollar was lower at noon as equity markets softened and uncertainty surrounded the leadership of the Australian Labor Party.

Toll says strength in resources activity and Toll's ability to win new contracts have offset weakness in the retail and industrial sectors.

Regional pay television operator Austar's full year net profit rises by 21 per cent despite a fall in customer numbers.

Australian shares lost ground by noon as sentiment was dampened by falls on overseas markets.