Fund Investigation Expands: 18-Year Decline Streak in Borsa Istanbul

The expansion of the fund investigation targeting capital markets increased the pressure on Borsa Istanbul, as the BIST 100 index recorded its longest weekly decline streak in the last 18 years, closing the sixth consecutive week in negative territory. While recent operations and new arrests carried out within the scope of the investigation heightened market anxiety, the number of detainees in the case reached 114.

Under the impact of the fund investigation targeting capital markets, the BIST 100 index in Borsa Istanbul completed the final trading day of the week with a 0.92 percent loss at 11,116.99 points. Dropping down to 10,772 points during the day, the index saw its lowest level since November 19, 2025. On Friday, October 23, the BIST 100 fell to 220.4 dollars in dollar terms, reaching its lowest level since June 2023. While the weekly loss of the index, which fell uninterrupted for six weeks, reached 5.16 percent, a similar length of decline streak was last seen in February 2008. While sales generally spread across sectors, losses in banking and industrial stocks drew attention.

In the latest operation regarding the fund investigation, 15 people including Taha Çakmak, former General Manager of Türkiye Sigorta and Türkiye Hayat Emeklilik, and İnan Altınbaş were detained. Nusret Altınbaş, the owner of Altınbaş Holding who had an arrest warrant against him, surrendered. With the new arrests, the total number of detainees in the investigation rose to 114. Among the detained names, Ertan Aydın, former chief advisor to President Erdoğan and former AKP Member of Parliament, was also referred to the courthouse.

Former Minister of Economy and AKP Deputy Chairman Nihat Zeybekci stated that there was negligence and abuse of office by certain public institutions in the fund investigation. Meanwhile, the precautionary measure on the assets of Astor Enerji AŞ partners Enver and Feridun Geçgel was lifted after they deposited 5 billion liras into the TMSF voluntary return account. While an arrest warrant was issued for former CMB (SPK) Head of Department Erman Çete, an investigation is being conducted against former CMB (SPK) President İbrahim Ömer Gönül on charges of misconduct.