Turkey's benchmark stock index fell 1.13 percent to close at 102,282.68 points on Thursday.
Borsa Istanbul's BIST 100 index started the day at 103,853.39 points, down 1,170.17 points from Wednesday's close of 103,452.85 points.
The benchmark index hovered between 102,263.98 and 104,194.20 points during Thursday's trading.
The total market value of the BIST 100 was around 672 billion Turkish liras ($124.9 billion) by market close, and the daily trading volume was 7.6 billion Turkish liras ($1.4 billion).
On the fourth transaction day of the week, 17 stocks on the index rose, 78 declined, and five were flat compared to the previous close.
The highest trading volumes were posted by the national flag carrier Turkish Airlines, private lender Garanti, and petrochemical company Petkim.
The shares of food giant Ulker were the top gainers -- up 7.82 percent -- and conglomerate Ihlas dropped the most, losing 12.50 percent.
The U.S. dollar/Turkish lira exchange rate climbed to 5.4370 at close, up from Wednesday's close of 5.4210.
The euro/lira rate also dropped to 6.1280 at Thursday's close, versus 6.1330 at last week's close.
One British pound traded for 7.1540 Turkish liras, while the GBP/TRY rate was 7.1360 at close on Wednesday.
In Borsa Istanbul's Precious Metals and Diamond Markets, the price of one ounce of gold was around $1,288.50 by market close, up from $1,287.30 at the previous close.
The price of Brent oil was around $65.90 per barrel as of 6 p.m. local time (1500GMT) on Thursday.
Source: Anadolu Agency