Turkey's benchmark stock index fell 5.26% to close at 1,034.40 points on Thursday.
After starting the day at 1,090.61 points, Borsa Istanbul's BIST 100 index was down by 57.40 points from Wednesday's close of 1,091.80 points.
During the day, the index hovered between 1,033.82 points and 1,093.68 points.
The total market value of the BIST 100 at close was 760 billion Turkish liras ($108 billion), with a daily trading volume of 23.5 billion Turkish liras ($3.2 billion).
Shares of glass manufacturer Sise Cam, real estate investment trust Emlak Konut GYO, and private lender Garanti BBVA saw the highest trading volumes.
Stocks of Koza Altin, the gold miner, did the best, rising 0.82%, while shares of Akcansa, a cement producer Akcansat, did the worst, losing 10%.
One ounce of gold sold for $2,064.20 by market close, up from $2,044.00 at the previous close, according to data from Borsa Istanbul's Precious Metals and Diamond Markets.
The price of Brent crude oil was around $45.64 per barrel as of 6 p.m. local time (1500GMT) on Wednesday.
At the beginning of this year, a barrel of Brent oil sold for around $58.
