The 24-share benchmark CROBEX index fell 1.09% to 2,148.63 points after rising 0.35% on Tuesday.
The narrower blue-chip index, CROBEX10, which tracks the 10 leading companies in terms of free-float market capitalisation and liquidity, closed down 1.93% at 1,116.5 on Wednesday.
The CROX index, which tracks the 12 most traded stocks on the ZSE and is calculated by the Vienna bourse, fell 1.29% in euro terms to 1,315.03 points.
Shares of HT-Hrvatske Telekomunikacije, majority-owned by Deutsche Telekom, edged down 0.14% to 271.62 kuna ($56.2/37.6 euro) in the day's highest turnover of some 9.7 million kuna.
ZSE's total turnover in floor trading fell to 28.6 million kuna from 39.3 million kuna on Tuesday.
The fixed-income CROBIS index closed unchanged at 90.32 points.
(1 euro = 7.2335 Croatian kuna)