Turkey's benchmark stock index started the week down 0.28% or 254.15 points to open at 90,335.58 points on Monday.
Following the morning session on Monday, the BIST 100 will go into a three-and-a-half-day break for the Muslim Eid al-Fitr holiday.
On Friday, Borsa Istanbul's BIST 100 index surged 0.64% to close the week at 90,589.73 points with a daily trading volume of 5.4 billion Turkish liras ($913 million).
Last week, the benchmark index posted a 5.24% hike, climbing 1.94% from 88,865.01 points at the close on the first business day of 2019.
The U.S. dollar/Turkish lira exchange rate stood at 5.8530 as of 9.30 a.m. local time (0630GMT) on Monday, versus 5.8400 at Friday's close.
The euro/Turkish lira exchange rate was 6,5390, compared to 6.5330, and one British pound traded for 7.4120 Turkish liras, up from 7.3780.
One barrel of Brent oil was sold for $61.24 as of 9.45 a.m. local time (0645GMT) on Monday.
By Muhammed Ali Gurtas