ANKARA (AA) - The BIST 100 index lost 231.46 points to open at 77,907.20 points on Monday morning during its first transactions.
The benchmark index decreased by 0.30 percent while the banking and holding sector indexes declined by 0.26 and 0.46 percent, respectively.
On the first trading day of the week, the investment trusts sector index increased the most, by 0.84 percent, while the electric index started the week with the biggest drop -- a 0.58 percent fall.
The U.S. dollar/Turkish lira exchange rate increased to 3.5380 at 9.30 a.m. local time (0630 GMT) on Monday, compared with 3.5230 at Thursday's close.
Gold held at $1,150.9 an ounce.
The U.S. crude futures was flat at $53.90 a barrel, while benchmark Brent crude futures slipped by 0.19 percent to reach $56.74.