The US stock market indices opened in the green on Monday.Benchmark equity indices tracked the gains in US and Asian markets to close higher on the first session of Christmas week.Overseas investors stayed net sellers for the sixth consecutive day and offloaded stocks worth approximately Rs 168.71 crore on Monday.Nifty ended 0.7% or 165.95 points up at 23,753.45, and Sensex closed 0.64% or 498.58 points higher at 78,540.17.HG Infra Engineering, PG Electroplast, Vraj Iron, and Steel, Zaggle Prepaid Ocean Services are some of the stocks to watch on Tuesday.Aster DM Healthcare appointed Nalanda Jayadev as chief executive officer.IIFL Capital Services' arm Livlong Protection received a corporate agent license from IRDAI.Symphony signed a second addendum regarding the loan agreement with arm Symphony AU.The Indian rupee weakened by 10 paise to close at a record low of 85.12 against the US dollar on Monday.Stocks worth observing include HG Infra Engineering, PG Electroplast, Vraj Iron and Steel etc.