STOCKS to watch on the Australian stock exchange at close on Friday: AQA - AQUILA RESOURCES - down 6.0 cents, or 2.7 per cent, at $2.16 AGK - AGL - up 12 cents, or 0.79 per cent, at $15.37 Energy giant AGL has increased its stake in rival Australian Power and Gas Company (APG) to more than 75 per cent and hopes to fast-track the remainder of its takeover process. BLY - BOART LONGYEAR - down one cent, or 2.02 per cent, to 48.5 cents The world's largest drilling company Boart Longyear has had its credit rating downgraded as it braces for a tough year ahead. CSL - CSL - up 62 cents, or 0.95 per cent, to $65.90 Former CSL boss Brian McNamee left the top position at blood products and vaccines supplier at the end of June with pay and entitlements worth almost $20 million.