Turkey's stock exchange started the week down 0.79 percent, or 751.29 points, to open at 94,132.17 points on Monday.
On the first transaction day of the week, the BIST banking and holding sector indices dropped 1.01 percent and 1.02 percent, respectively.
Among all sector indices, the mining sector index posted the best performance, up 0.26 percent, while the holding sector index did the worst.
Last week, Borsa Istanbul's BIST 100 closed Friday at 94,883.47, up 0.41 percent, or 386.67 points, with a trading volume of 7.2 billion Turkish liras (around $1.16 billion).
The U.S. dollar/Turkish lira exchange rose to 6.1650 as of 9.30 a.m. local time (0630GMT), up from Friday's close of 6.1280.
The euro/Lira exchange rate also climbed to 7.1020 by market open on Monday -- from 7.0640 at the previous close -- and one British pound traded for 8.0690 Turkish liras versus 8.0370 at the previous close.
The price of Brent oil stood at $83.55 per barrel as of 10.00 a.m. local time (0700GMT) Monday, compared to $84.70 on Friday.