Stocks to watch on the Australian stock exchange on Monday, April 20:

AGL – AGL ENERGY – down nine cents, or 0.6 per cent, at $14.98

Electricity giant AGL will close its coal fired power stations by 2050 under a new greenhouse gas policy.

PSA – PETSEC – down 0.5 cents, or 4.6 per cent, at 10.5 cents

Oil and gas producer Petsec Energy has struck a deal with Oil Search to take over the operation of an exploration area in Yemen.

RIO – RIO TINTO – down 78 cents, or 1.4 per cent, at $55.09

BHP – BHP BILLITON – down 26 cents, or 0.9 per cent, at $29.97

FMG – FORTESCUE METALS – down 8.5 cents, or 4.4 per cent, at $1.87

Rio Tinto has defended increasing iron ore production even as prices plunge, arguing that being a low cost miner allows it to thrive in the face of continued market volatility which is causing smaller players “significant distress”.

STO – SANTOS – up three cents, or 0.4 per cent, at $7.96

Oil and gas producer Santos has suffered a steep fall in quarterly sales revenue because of falling oil prices.

SYD – SYDNEY AIRPORT – down three cents, or 0.6 per cent, at $5.37

Trevor Gerber will replace Max Moore-Wilton as the chairman of Sydney Airport in May.

TLS – TELSTRA – down nine cents, or 1.4 per cent, at $6.14

Pay TV company Foxtel’s chairman Robert Nason is stepping down from a leadership role at Telstra.

TWE – TREASURY WINE ESTATES – down five cents, or 0.9 per cent, at $5.64

The maker of Penfolds has refinanced $300 million in debt to extend the length of its loan.

WHC – WHITEHAVEN COAL – up one cent, or 0.7 per cent, at $1.55

Whitehaven Coal has increased its full year production target to 7.2 million tonnes, up from 7.0 million tonnes after a boost in March quarter production.