NextFin News - Turkey's market regulator has filed criminal complaints over stock trading as prosecutors opened an investigation into a former Borsa Istanbul chairman, the latest escalation in a crackdown that follows a fund-driven rout which sent the BIST 100 as much as 7.7 percent lower in a single session. The Capital Markets Board's move, confirmed Wednesday, comes after new rules forced asset managers to unwind illiquid holdings, triggering a run on investment funds that spilled into the broader equity market.
The Crash That Started in the Fund Complex
Turkey's benchmark index closed at 13,122.58 on September 16, down 5.54 percent, after falling as far as 7.7 percent intraday. The decline was severe enough to trigger the exchange's Index-Based Circuit Breaker, temporarily halting all equity trading. But the shock did not originate in equities. It began in the fund complex, where a regulatory change forced asset managers to sell assets that had few buyers.
On August 28, the Capital Markets Board, known locally as SPK, overhauled its Guideline on Investment Funds in Bulletin 2026/54. The new limits took effect the following day and reshaped the rules for hedge funds, or Serbest Fon, and the portfolio management companies that run them. The board tightened investment diversification requirements, raised capital adequacy standards, and imposed tiered ownership caps based on free-float ratios. Existing hedge fund positions above the new caps were frozen immediately, with a graduated unwind: reduce one-third of the excess by October 31, two-thirds by November 30, and eliminate it entirely by December 31.
The regulations targeted a specific practice: funds loading up on illiquid, low-free-float stocks, often tied to affiliated parties, to inflate reported returns. Global index providers, including MSCI, had flagged transparency concerns around these concentrated holdings. The fix was sound in principle. In execution, it created a forced seller of assets that could not absorb large sales without moving the price.
Two asset managers reached the breaking point first. Pusula Portfoy, which oversees roughly $13 billion in assets, said in an exchange filing that it failed to meet some investor redemption requests, citing reconciliation and liquidity management issues with brokerage firms. Tera Portfoy Yonetim AS followed, saying two of its funds with a combined 366 billion lira, about $7.5 billion, in assets could not meet redemption requests. The defaults hit Tera Portfoy Money Market Fund (TP2) and Tera Portfoy Equity Intensive Fund (THF), the firm's second- and third-largest funds, with portfolio sizes of 224 billion lira and 142 billion lira respectively, according to Turkey's fund data platform Tefas. Atlas Portfoy also said it would limit redemptions on one fund. Tera Group said it has a deal to acquire the Pusula group, but stressed the funds are not yet its legal responsibility while regulatory approvals are pending.
Tera had become a focal point for concerns over the risks created by funds building large, concentrated positions in relatively illiquid Turkish stocks. The firm's main investment funds had attracted a cult following on social media for astronomical returns, achieved by pouring billions of lira into a tight circle of related companies. Tera Chairman Emre Tezmen described the pressure as an "extraordinary and unprecedented" speculative attack that risked spreading across the markets.
Retail investors pulled roughly $1 billion, approximately 550 billion lira, from local investment funds in a single day. Since late August, Turkish funds have seen cumulative outflows of about 128.7 billion lira, roughly $2.7 billion. The September 16 exodus was the crescendo of a trend that had been building for weeks.
"Turkey's Financial Stability Committee said it will convene at 8 a.m. on Thursday, Sep. 17," to address the stress, according to reporting on the emergency session.
Enforcement Follows the Rout
Against that backdrop, the Capital Markets Board filed criminal complaints over stock trading, referring its findings to prosecutors. Under Turkish capital markets law, the regulator's standard enforcement path is to file a criminal complaint with the Chief Public Prosecutor's Office when it identifies conduct that may constitute market fraud or manipulation. The board has used that route repeatedly in recent years.
"The Board files a criminal complaint with the Chief Public Prosecutor's Office in order to ensure the punishment of persons who engage in the capital market," the Capital Markets Board said in a statement outlining its enforcement powers.
Prosecutors are also pursuing parallel investigations into market abuse and market speech. The Istanbul Chief Public Prosecutor's Office opened an inquiry into Ibrahim Mustafa Turhan, who chaired Borsa Istanbul from 2012 to 2015 and previously served as a deputy governor of the Turkish central bank, over posts on his X account, @ibrahimmturhan2, that authorities alleged could "cause fear and panic" among investors in stocks and other financial instruments. Prosecutors did not announce a detention order, did not say Turhan's comments contained false information, and did not allege that he had traded securities.
Turhan, a former AKP member of parliament and economist, posted a lengthy commentary after the circuit breaker tripped, arguing that there was no fundamental or structural risk in the Turkish equity market and urging investors to remain calm. He wrote that companies with sound profitability and free cash flow were "priced below their value" and that there was "no clear and imminent threat" on the currency or public finances.
A separate case, opened by the Bakirkoy Chief Public Prosecutor's Office over social media posts alleged to contain false or misleading information intended to influence prices or investor decisions, has led to the detention of six people, with prosecutors seeking to identify the owners of 11 other accounts.
And on September 10, authorities detained four suspects in a probe into the X account "bySerez" over allegedly manipulative posts from 2023 concerning nine Borsa Istanbul shares. Detention orders were issued for five suspects on charges of "information-based market fraud," and one person remains at large.
This is not Turkey's first manipulation crackdown. In September 2025, prosecutors detained 14 officials of Investco Holding over alleged manipulation that caused losses to small investors, after finding unnatural increases in trading volumes and share prices. In May 2025, another operation detained 15 suspects over suspicious activity in Borsa Istanbul equities, following a March 2025 probe that targeted 17 people. In November 2025, the government signaled plans to double jail terms and fines for market manipulation, a legislative push that the current wave of complaints appears designed to support.
The Mechanism: A Regulatory Fix That Broke Liquidity
The transmission chain is textbook, and it runs in one direction. A regulator caps concentrated, illiquid holdings. Fund managers must sell. The only buyers for those stocks are other funds running the same unwind. Prices fall. Fund net asset values drop. Investors request redemptions. Managers sell more illiquid stock to raise cash. Prices fall further. What began as a portfolio rule became a liquidity mismatch, and the liquidity mismatch became a run.
This is not a leverage-driven crash in the mold of the 2022 VIOP rout, when margin calls on futures positions forced brokerages to liquidate collateral and banking shares fell 39 percent in a three-week decline. The 2026 episode is a redemption-driven crash: the forced seller is the fund manager, not the leveraged retail trader, and the amplification runs through net asset values and redemption gates rather than margin accounts and broker balance sheets.
The distinction matters for the policy response. Margin crises are solved with liquidity backstops and capital injections into intermediaries. Redemption crises are solved with time: gates, suspension windows, and orderly wind-downs that break the link between daily liquidity promises and illiquid assets. Turkey's Financial Stability Committee meeting on September 17 was the first test of whether authorities understand which crisis they are facing.
The second-order consequence is what should worry policymakers most. A fund run of this kind does not stop at the funds themselves. It transmits into the index through the weight of the affected names, into brokerages that lent against the same collateral, and into retail confidence that had been rebuilt over months of steady gains. Once investors learn that a fund can gate redemptions, the rational response is to exit earlier next time — which makes the next shock arrive faster. That is the paradox of redemption gates: they buy time for the manager but accelerate the run on everyone else.
The Turhan Question: Policing Panic or Chilling Speech?
The Turhan investigation is the most delicate element of the enforcement wave. Prosecutors' statement did not identify the specific law he is suspected of breaching. Turkey's capital markets law carries penalties of up to five years in prison for spreading false or deceptive information that affects markets. But the authorities have not alleged that Turhan's analysis was false — only that its tone risked alarming investors.
Regulators everywhere walk a narrow line between policing market manipulation and protecting legitimate commentary. In developed markets, the test typically turns on whether a statement is knowingly false and whether the speaker has a position to profit from the move. A former exchange chairman calling for calm during a selloff does not fit the usual profile of a manipulator — unless prosecutors can show the comments were part of a scheme to distort prices.
The risk for Borsa Istanbul is a chilling one. If market participants conclude that measured commentary during volatility can draw a criminal investigation, liquidity providers may pull back precisely when the market needs them most. That would make future circuit-breaker events more severe, not less. Enforcement that restores confidence among retail investors who lost money to manipulated names is one thing. Enforcement that makes every public comment a legal risk is another.
There is also a question of consistency. The same authorities pursuing Turhan for posts alleged to spread panic are simultaneously prosecuting the bySerez account for posts alleged to pump stocks. Both cases rest on the proposition that speech moves prices. If speech that inflates prices is a crime, then speech that calms a falling market sits on the same continuum — and the line between the two is drawn by prosecutors, not by the market.
What This Means for Investors
In the short term, the enforcement wave is likely to keep a lid on speculative momentum in the small-cap and low-free-float names that were the focus of the new CMB rules. The bySerez and Bakirkoy operations show regulators are willing to pursue "information-based market fraud" across social media channels and to reach back in time — the bySerez posts date to 2023.
For foreign investors, the signal is mixed. A regulator that actively polices manipulation is a positive governance signal for an emerging market that has long battled a reputation for opaque trading. The CMB's move against concentrated affiliated-party holdings addresses a real transparency problem that index providers had flagged. But the breadth of the speech-related probes raises questions about where the enforcement perimeter ends.
The index-membership question looms larger. MSCI and other global index providers have already flagged transparency concerns around concentrated Turkish holdings. If the fallout from the CMB's forced unwind leads to sustained volatility or trading suspensions, index committees may reassess the investability of affected names — and by extension, the weight Turkey carries in emerging-market benchmarks. That would turn a domestic liquidity event into a structural outflow channel, as passive mandates adjust their exposure. The risk is not imminent, but it is the second-order path that turns a fund problem into a country-allocation problem.
The macro backdrop adds another layer. The central bank held its policy rate at 37 percent at its September 10 meeting, the fifth straight hold, as it tries to anchor inflation expectations. The lira traded around 47.9 against the dollar in the wake of the equity turbulence. A stable policy rate does not guarantee stable asset prices when the shock is coming from fund flows and forced selling rather than monetary policy.
The short-selling ban, extended repeatedly by the CMB through 2026, also plays into the fragility. It was meant to dampen volatility. In practice, it removes a key source of two-way liquidity and price discovery, leaving the market more prone to one-directional moves when sentiment turns. A market that cannot short efficiently is a market where bad news arrives all at once.
What to Watch Next
Three signals will determine whether this episode becomes a lasting regime shift or a contained enforcement cycle. First, the outcome of the Financial Stability Committee's September 17 meeting: temporary redemption gates, backstop liquidity facilities, or accelerated restructuring of troubled funds are all tools available, and the choice will reveal whether authorities see this as a liquidity problem or a solvency problem. Second, whether prosecutors move beyond investigations to formal indictments, and on what charges — the Turhan case in particular will set the tone for what counts as actionable speech in Turkish markets. Third, whether the forced selling abates as funds approach the CMB's staggered deadlines of October 31, November 30, and December 31.
The strongest counter-thesis is that the crackdown is exactly what the market needs: that without aggressive enforcement, the affiliated-party schemes and social-media pump operations would have continued to extract wealth from retail investors until confidence collapsed entirely. On this view, short-term volatility is the price of cleaning up a market that had drifted toward a two-tier structure — liquid blue chips for foreigners, manipulated small caps for locals. The counter-argument is credible so far as it concerns trading abuse. It is far less persuasive when applied to commentary: prosecuting a former exchange chairman for urging calm does not clean up a market, and it does not fit the definition of manipulation in any developed jurisdiction.
The falsifying signal is specific and observable. If the Financial Stability Committee announces broad redemption gates combined with a liquidity backstop, and the BIST 100 holds above the circuit-breaker trigger through the first CMB unwind deadline on October 31 without further fund defaults, then this was a contained liquidity event and the enforcement wave will pass as a governance positive. If instead more asset managers miss redemption payments after September 17, or if the Turhan case advances to formal charges without an allegation of a trading position or demonstrably false statements, then the episode is becoming a structural liquidity and speech-risk problem — and the appropriate response is not more prosecutions but a recalibration of fund liquidity rules and enforcement scope.
Base case: the committee provides liquidity backstops and orderly wind-downs for the troubled funds, forced selling slows as positions are restructured, and the BIST 100 stabilizes above the circuit-breaker zone. Upside case: authorities pair enforcement with market-structure reforms that improve two-way liquidity — including a calibrated easing of the short-selling ban — and foreign capital returns on improved governance credentials. Downside case: redemption gates prove insufficient, more funds miss payments, and the Turhan precedent widens so that commentary risk keeps liquidity providers on the sidelines, leaving Borsa Istanbul vulnerable to the next forced unwind.
The central judgment: Turkey's regulators are right to pursue genuine market abuse and to close the loopholes that let funds juice returns with illiquid affiliated holdings. But criminal complaints cannot repair a market whose fragility comes from a maturity mismatch between daily redemption promises and assets that cannot be sold quickly. The enforcement wave may restore some confidence among the retail investors who lost money. It will not, by itself, make the next run less likely. That requires fixing the plumbing — aligning fund liquidity with fund promises — not just prosecuting the players.
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