Turkey’s benchmark index closed the day down 675.93 points Monday to stand at 98,191.97 points.
Borsa Istanbul's BIST 100 index decreased 0.68 percent with a total trading volume of 5.5 billion Turkish liras (approximately $1.56 million).
On the first transaction day of the week, the banking and holding sector indices declined by 0.72 percent and 1.09 percent, respectively.
Among all indices, the leasing and factoring sector index was the best performer, up 2.4 percent, while the tourism sector index was the worst, down 1.99 percent.
The stocks of Sasa Polyester Sanayi (SASA), a leading polyester producer, enjoyed the biggest rise with a 14.37 percent hike, while the stocks of conglomerate Tekfen Holding (TKFEN) -- involved in oil, power generation, construction and infrastructure -- saw a 4.5 percent decrease, marking the biggest drop of the day.
The five most-traded stocks were national flag carrier Turkish Airlines, private lenders Garanti and Akbank, state lender Halkbank and a real estate investment partnership Emlak Konut GYO.
The U.S. dollar/Turkish lira exchange rate slightly rose to 3.5220 Turkish liras as of 5 p.m. (1400GMT) on Monday, up from 3.5150 Turkish liras at Friday's close.
Borsa Istanbul's Gold Exchange index increased 0.65 percent, while the price of gold per kilogram rose to 142,000 Turkish liras (around $40,241) as of 4.30 p.m. (1330GMT).
Turkey's monthly inflation rate rose in May, but annual inflation eased to 11.72 percent from 11.87 percent in April, the Turkish Statistical Institute (TurkStat) announced on Monday.
Consumer prices in the country climbed 0.45 percent month-on-month in May, TurkStat said.