Turkey's benchmark stock index started the day with an decrease of 0.43 percent or 446.09 points to open at 103,676.77 points on Monday.
On the first transaction day of the week, the banking and holding sector indices were down 0.26 and 0.39 percent, respectively.
Among all sectors, the only textile leather sector index was up 0.02 percent, while the mining sector index started the day with the biggest fall, down 2.14 percent.
The BIST 100 closed at 104,122.85 points after increasing 0.12 percent on Friday, with a 3.8 billion Turkish lira (approximately $1.08 billion) trade volume.
The U.S. dollar/Turkish lira exchange rate increased to 3.4990 at 9.30 a.m. local time (0630GMT) on Monday, compared with 3.5030 at Friday's close.
