Turkey's benchmark stock index dropped 0.30 percent or 266.76 points to open at 89,695.14 points on Tuesday.
On Monday, Borsa Istanbul's BIST 100 index fell 0.63 percent to close the day at 89,961.91 points with a daily trading volume of 3.5 billion Turkish lira ($650 million).
The U.S. dollar/Turkish lira exchange rate stood at 5.3790 as of 9.30 a.m. local time (0630GMT), compared with Monday's closing rate of 5.3770.
The euro/Turkish lira exchange rate also stood at 6.1050, versus 6.1060 at the last close. One British pound traded for 6.8070 Turkish liras, as the GBP/TRY exchange rate was 6.8000 by market close on Monday.
The price of Brent oil dropped to $58.73 per barrel as of 10.00 a.m. local time (0700GMT) Tuesday, versus $60.01 on Monday's closing.