Borsa Istanbul updates free-float ratios for nine shares effective September 30
Borsa Istanbul updated the free-float ratios used in index calculations for nine companies. The change does not alter company capital or an investor's share count, though it can affect index weights and passive-fund flows.
Three critical developments
- From September 30, index calculations use 11% for AKCNS, 73% for AVGYO, 64% for DMRGD, 35% for EFOR and 73% for OSTIM.
- The applicable ratios are 79% for SAMAT, 31% for TRHOL, 24% for UFUK and 22% for ZGYO.
- The filing omits prior ratios, so it cannot by itself quantify how much each share's index weight rises or falls.
Free-float ratios effective September 30, 2026
The nine ratios Borsa Istanbul said it will use in index calculations.
| Ticker | Company | Free float | Effective |
|---|---|---|---|
| AKCNS | Akçansa | 11% | September 30, 2026 |
| AVGYO | Avrasya REIT | 73% | September 30, 2026 |
| DMRGD | DMR Unlu Mamuller | 64% | September 30, 2026 |
| EFOR | Efor Yatırım | 35% | September 30, 2026 |
| OSTIM | Ostim Endüstriyel Yatırımlar | 73% | September 30, 2026 |
| SAMAT | Saray Matbaacılık | 79% | September 30, 2026 |
| TRHOL | Tera Finansal Yatırımlar Holding | 31% | September 30, 2026 |
| UFUK | Ufuk Yatırım | 24% | September 30, 2026 |
| ZGYO | Z REIT | 22% | September 30, 2026 |
What is changing?
Borsa Istanbul updated the free-float ratios used in its indices for nine shares. The filing was published September 29 and all listed ratios become effective on September 30, 2026.
Which ratios will apply?
The list sets AKCNS at 11%, AVGYO at 73%, DMRGD at 64%, EFOR at 35%, OSTIM at 73%, SAMAT at 79%, TRHOL at 31%, UFUK at 24% and ZGYO at 22%. The notice covers only those nine shares.
Why does free float matter?
BIST indices use the investable free-float portion rather than a company's entire outstanding share base when calculating weights. A higher ratio can increase calculated investable market value, all else equal; a lower ratio can reduce it. Net impact still requires the prior ratio, price, shares outstanding and index method.
Is this a capital action?
No. The notice is not by itself a rights issue, bonus issue, split, dividend or transaction changing the number of shares in an investor account. It updates an index-calculation input; paid-in capital must be checked through separate issuer filings.
How might passive funds respond?
A fund fully replicating an affected index may need to rebalance when the index provider applies new weights. The filing does not disclose any fund's certain trade size, timing or direction. Fund size, tracking method and simultaneous component changes can alter the outcome.
Method and limitations
This report uses only the ratios and date in the official filing. Because prior ratios are absent, we do not calculate percentage-point changes or estimated fund flows. No price, volume or return forecast is made; this is not investment advice.
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