The ASX is up 45 points with the Energy sector driving the gains.

Of the 50 largest stocks, the most movement has been from Resmed (ASX:RMD) which is higher by 6.50%, AGL Energy which is higher by 3.37%, and Whitehaven Coal which is higher by 3.33%.

As the Top 50 largest companies comprise almost 60% of the total market, any big changes to their share price may influence the overall market.

The biggest gainer on the ASX at mid-session is Volt Power Group (ASX:VPR) - this is a micro cap company.

The biggest loser on the ASX at mid-session is Cyclone Metals (ASX:CLE) - this is a micro cap company.