Turkey's benchmark stock index dropped 0.16%, or 190.72 points, on Wednesday, to start the day at 121,232.62 points.
At Tuesday's close, Borsa Istanbul's BIST 100 index was up 0.98% at 121,423.34 points, the highest closing level in its history, with a daily trading volume of 14 billion Turkish liras ($2.4 billion).
The U.S. dollar/Turkish lira exchange rate stood at 5.8850 as of 9.30 a.m. local time (0630GMT) on Wednesday, inching up from 5.8840 at Tuesday's close.
The euro/Turkish lira exchange rate rose to 6.5540, versus 6.5390, and one British pound traded for 7.6910 Turkish liras, versus 7.6630 at the previous close.
One barrel of Brent crude oil sold for around $64.40 as of 10 a.m. local time (0700GMT) on Wednesday.