Turkey's benchmark stock index BIST 100 started the day at 108,167.46 with a decrease of 0.3 pct or 321.23 points on Monday.
On the first transaction day of the week, the banking and holding sector indices dropped 0.48 percent and 0.47 percent, respectively.
Among all sectors, the nonmetal mining product sector index was the best performer, rising 0.08 percent, while the sports sector index fell the most, seeing a 0.59 percent decline.
The lira started over 3.69 against the U.S. dollar at 9.30 a.m. local time (0630GMT), weakening from 3.6710 at Friday's close.
The Turkish currency also weakening against the European single currency at 4.349 to the euro, a decrease of 0.5 percent.
On Monday, the Turkish Statistical Institute (TurkStat) said the country’s consumer confidence dropped by two percent month-on-month to stand at 67.3 in October.
On Tuesday, September house sales and October business confidence index will be released by TurkStat and capacity utilization rate on Wednesday.
Ministers, including Mehmet Simsek who is responsible for the Turkish economy, will attend a meeting of the country’s economic coordination committee on Monday (0800GMT) under Prime Minister Binali Yildirim.
Turkey's benchmark stock index closed the day up 0.05 percent at 108,488.69 points with a trade volume of 6.2 billion Turkish liras ($1.68 billion) on Friday.
