Journals / Tarım Bilimleri Dergisi / 2026 / Volume: 32 Issue: 2

Speculative Bubbles in Regional Wheat Markets: Evidence from Türkiye

Ali Berk(Tarımsal Araştırmalar ve Politikalar Genel Müdürlüğü)0000-0003-3912-9656
Yusuf Ünsal(Department of Economics, Anadolu University)0000-0002-7856-5402
Derviş Durmaz(Ministry of Agriculture and Forestry, Field Crops Central Research Institute)0000-0002-7061-8418
Pages
—
Publication Date
2026-03-24
🏛️Bibliographic metadata and full text access for this article are provided via DergiPark.
DergiPark Record ↗
✨

AI Summary & Key Takeaways

AI Insight
⚡ TL;DR(Too Long; Didn't Read)

Real-time monitoring and analysis of wheat exchange prices would allow timely intervention when price bubble signals emerge.

📌 3 Key Takeaways

🎯
Objective & Hypothesis:Despite its strategic role in the wheat trade, Türkiye’s wheat markets remain vulnerable to volatile price movements and speculative behavior.
📊
Key Findings & Data:While significant progress has been made in the global literature on detecting speculative bubbles in agricultural commodities, there is a clear empirical gap in applying advanced econometric bubble detection methods to the wheat sector in Türkiye.
💡
Conclusion & Impact:Real-time monitoring and analysis of wheat exchange prices would allow timely intervention when price bubble signals emerge.
🔬Design:Modeling & Simulation
📍Scope:2020 Verileri
⚙️Variables:Effect Speculative bubbles · Price volatility · GSADF test

Abstract

Despite its strategic role in the wheat trade, Türkiye’s wheat markets remain vulnerable to volatile price movements and speculative behavior. While significant progress has been made in the global literature on detecting speculative bubbles in agricultural commodities, there is a clear empirical gap in applying advanced econometric bubble detection methods to the wheat sector in Türkiye. This study aims to address this issue by offering region-specific insights into the speculative dynamics that influence wheat prices in major production centers in Türkiye. We applied the Supremum Augmented Dickey-Fuller (SADF) and Generalized Supremum Augmented Dickey-Fuller (GSADF) tests to monthly wheat price data from Ankara, Edirne, and Konya provinces to detect speculative price bubbles. After identifying bubble periods, we used probit and logit models to explore potential drivers, including the producer price index (UFE), input price index (IPI), real effective exchange rate (R), and the marketed quantity of wheat (LNQ). The empirical results revealed multiple statistically significant bubble episodes in Ankara and Edirne between 2020 and 2022. In contrast, Konya exhibited fewer, shorter-lived bubbles concentrated in 2023–2024. GSADF results confirmed that price exuberance was neither uniformly distributed nor persistent across provinces. Regression analyses showed that the UFE and IPI significantly increased the probability of bubble formation in Ankara and Konya. Meanwhile, R had a stabilizing effect in Ankara and Edirne. These results imply regional differences in speculative price behavior within Türkiye’s wheat market. The results highlight the importance of incorporating localized market structures and macroeconomic indicators into national agricultural price stabilization policies. Methodologically, this study contributes by integrating recursive right-tailed unit root tests with nonlinear probability models to better understand speculative forces in commodity markets. As a policy recommendation, the licensed warehousing system should be revised to enable physical and/or online transactions through regionally authorized procurement centers. Real-time monitoring and analysis of wheat exchange prices would allow timely intervention when price bubble signals emerge.

🔖

Cite This Article

Berk, A., Ünsal, Y., Durmaz, D. (2026). Speculative Bubbles in Regional Wheat Markets: Evidence from Türkiye. Tarım Bilimleri Dergisi, Volume: 32 Issue: 2. https://doi.org/10.15832/ankutbd.1774473

📄 Full Text PDF Viewer

📄

PDF görüntüleyici hazırlanıyor...

References (41)

  1. Adämmer Y & Bohl M T (2022). Food price bubbles: Food price indices of Turkey, the FAO, the OECD, and the IMF. Sustainability 15(13): 9947. https://doi.org/10.3390/su15139947
  2. Areal F J, Balcombe K & Rapsomanikis G (2016). Testing for bubbles in agriculture commodity markets. Economía Agraria y Recursos Naturales-Agricultural and Resource Economics 16(1): 59-79. https://doi.org/10.7201/earn.2016.01.04
  3. Chen Z, Yan B & Kang H (2023). Price bubbles of agricultural commodities: evidence from China’s futures market. Empirical Economics, 64(1): 195-222. https://doi.org/10.1007/s00181-022-02254-0
  4. Dastagiri M B & Bhavigna L (2019). The theory of agricultural price bubble & price crash in global economy. Applied Economics and Finance, 6(5): 168-176. https://doi.org/10.11114/aef.v6i5.4464
  5. Demir H & Ersoy B (2019). Volatility dynamics in Turkish wheat prices: An ARMA-GARCH approach. Journal of Agricultural Economics, Issue: 3 (3). (In Turkish). Tarım Ekonomisi Dergisi. Sayı:3 (3). https://doi.org/10.24181/tarekoder.658948
  6. EMBO Reports (2011). The speculator’s bread: what is behind rising food prices? EMBO Reports, 12(4). https://doi.org/10.1038/embor.2011.38
  7. Etienne X L, Irwin S H & Garcia P. (2014). Price explosiveness, speculation, and grain futures prices. American Journal of Agricultural Economics, 97(1), 65–87. https://doi.org/10.1093/ajae/aau069
  8. Etienne X, Irwin S H & Garcia P. (2020). Price bubbles in agricultural commodity futures markets. American Journal of Agricultural Economics, 102(2): 553–570. https://doi.org/10.1108/CAER-10-2019-0190
  9. Evans G W (1991). Pitfalls in testing explosive bubbles in asset prices. The American Economic Review 81(4): 922-930. https://www.researchgate.net/publication/4719474_Pitfalls_in_Testing_for_Explosive_Bubbles_in_Asset_Prices
  10. FAO (2024). Food Price Index. https://www.fao.org/worldfoodsituation/foodpricesindex/en/
  11. Fang M, Lin Y & Chang C L (2023). Positive and negative price bubbles of Chinese agricultural commodity futures. Economic Analysis and Policy 78: 456-471. https://doi.org/10.1016/j.eap.2023.03.023
  12. Flood R & Hodrick R (1990). On testing for speculative bubbles. J. Econ. Perspect. 4: 85–101. https://pubs.aeaweb.org/doi/pdfplus/10.1257/jep.4.2.85
  13. Güneri Ö İ & Durmuş B (2020). Dependent dummy variable models: An application of logit, probit and Tobit models on survey data. International Journal of Computational and Experimental Science and Engineering, 6(1): 63-74. https://dergipark.org.tr/en/download/article-file/1009887
  14. Gürkaynak R S (2008). Econometric tests of asset price bubbles: taking stock. Journal of Economic Surveys, 22(1): 166-186. https//doi.org/10.1111/j.1467-6419.2007.00530.x
  15. Huang W & Wang Y (2024). Identifying price bubbles in global carbon markets: Evidence from the SADF test, GSADF test and LPPLS method. Energy Economics, 134, 107626. https://doi.org/10.1016/j.eneco.2024.107626
  16. Kaya O & Uslu A (2021). Transmission of global oil and currency shocks to Turkish wheat prices. Economics and Policy. Vol 6(2). (In Turkish) Ekonomi ve Politika. Sayı: 6(2). https://doi.org/10.30784/epfad.687997
  17. Khan K, Su C W & Khurshid A (2022). Do booms and busts identify bubbles in energy prices. Resources Policy. Volume 76. https://doi.org/10.1016/j.resourpol.2022.102556
  18. Kılıç O & Giray F H (2021). Turkey’s Competitive Power in the International Wheat Market. Eurasian Journal of Agricultural Economics (EJAE), 1(1): 52-64. https://dergipark.org.tr/tr/download/article-file/3829075
  19. Kindleberger C P (2008). Bubbles in History in the New Palgrave Dictionary of Economics. In: Durlauf, S.N., Blume, L.E. (Eds). Palgrave Macmillan, Basingstoke. The New Palgrave Dictionary of Economics, 2nd edition, 2008. https://link.springer.com/rwe/10.1057/978-1 349-95121-5_3073-1
  20. Lagi M, Bar-Yam Y, Bertrand K Z & Bar-Yam Y (2011). The food crises: A quantitative model of food prices including speculators and ethanol conversion. https://arxiv.org/pdf/1109.4859
  21. Li J, Chavas J P, Etienne X L & Li C (2017). Commodity price bubbles and macroeconomics: evidence from the Chinese agricultural markets. Agricultural economics 48(6): 755-768. https://doi.org/10.1111/agec.12372
  22. Liaqat A, Nazir M S & Ahmad I (2019). Identification of multiple stock bubbles in an emerging market: application of GSADF approach. Economic Change and Restructuring 52: 301-326. https://doi.org/10.1007/s10644-018-9230-0
  23. Long J S & Freese J (2006). Regression models for categorical dependent variables using Stata (Vol. 7). College Station, Texas: Stata Press. MDPI (2021). Short-term speculation affects agricultural commodity returns and volatility in the European market prior to and during the pandemic. Agriculture, 12(5), 623. https://doi.org/10.3390/agriculture12050623
  24. MDPI (2022). Financial speculation impact on agricultural and other commodities return volatility: Implications for sustainable development and food security. Agriculture, 12(11), 1892. https://doi.org/10.3390/agriculture12111892
  25. Nusair S A (2012). Nonlinear adjustment of Asian real exchange rates. Economic Change and Restructuring, 45(3): 221-246. https://doi.org/10.1007/s10644-011-9116-x
  26. Pavlidis E G, Paya I & Peel D A (2017). Testing for speculative bubbles using spot and forward prices. International Economic Review, 58(4): 1191-1226. https://doi.org/10.1111/iere.12249
  27. Phillips P C &Yu J (2011). Dating the timeline of financial bubbles during the subprime crisis. Quantitative Economics, 2(3): 455-491. https://doi.org/10.3982/QE82
  28. Phillips P C, Wu Y & Yu J (2011). Explosive behavior in the 1990s Nasdaq: When did exuberance escalate asset values? International Economic Review 52(1): 201-226. https://doi.org/10.1111/j.1468-2354.2010.00625.x
  29. Phillips P C B, Shi S & Yu J (2012). Testing for multiple bubbles”. Cowles Foundation Discussion Paper, 1843. Yale University. https://elischolar.library.yale.edu/cgi/viewcontent.cgi?article=3201&context=cowles-discussion-paper-series
  30. Phillips P C, Shi S & Yu J (2015). Testing for multiple bubbles: Historical episodes of exuberance and collapse in the S&P 500. International Economic Review, 56(4), 1043-1078. http://korora.econ.yale.edu/phillips/pubs/art/p1498.pdf
  31. Şengül Z (2023). Fluctuations in Table Olive Prices in Türkiye: An Analysis of Volatility Using the ARIMA–GARCH Approach. (In Turkish) Türkiye'de Sofralık Zeytin Fiyatlarındaki Dalgalanmalar: ARIMA-GARCH Yaklaşımıyla Volatilite Araştırması. ANADOLU, J. of AARI. 2023, 33 (2): 281-295. https//doi.org/10.18615/anadolu.1385394
  32. Shiller R J, Fischer S & Friedman B M (1984). Stock prices and social dynamics. Brookings Papers on Economic Activity, 1984(2): 457-510. https://www.brookings.edu/wp-content/uploads/1984/06/1984b_bpea_shiller_fischer_friedman.pdf
  33. Tirole J (1982). On the possibility of speculation under rational expectations. Econometrica: Journal of the Econometric Society, 1163-1181. https://doi.org/10.2307/1911868
  34. Tirole J (1985). Asset bubbles and overlapping generations. Econometrica: Journal of the Econometric Society, 1499-1528. https://doi.org/10.2307/1913232
  35. TURKSTAT (2025). Prices Statistics. Turkish Statistical Institute. http://www.turkstat.gov.tr
  36. Urak F, Bilgic A, Bozma G, Florkowski W J & Efekan E (2022). Volatility in Live Calf, Live Sheep, and Feed Wheat Return Markets: A Threat to Food Price Stability in Turkey. Agriculture 12(4): 566. https://doi.org/10.3390/agriculture12040566
  37. Vasilopoulos K, Pavlidis E, Spavound S & Martíez-García E (2020). Exuber: Econometric Analysis of Explosive Time Series. R package version 0.4.1. https://github.com/kvasilopoulos/exuber.
  38. Yılmaz A M & Tomar O (2022). An Evaluation of Wheat Self-Sufficiency and Import Dependency in Türkiye. European Journal of Science and Technology. (In Turkish). Türkiye’de Buğdayın Kendi Kendine Yeterlilik ve İthalata Bağımlılık Açısından Değerlendirilmesi. Avrupa Bilim ve Teknoloji Dergisi (41): 449-456. https://doi.org/10.31590/ejosat.1192874
  39. Wang J, Ma K, Zhang L & Wang J (2022). Study on price bubbles of China’s agricultural commodity against the background of big data. Electronics, 11(24): 4067. https://doi.org/10.3390/electronics11244067
  40. Zhang X X, Liu L, Su C W, Tao R, Lobonţ O R & Moldovan N C (2019). Bubbles in agricultural commodity markets of China. Complexity, 2019(1): 2896479. https://doi.org/10.1155/2019/2896479
  41. Urak F, Bilgic A, Bozma G, Florkowski W J & Efekan E (2022). Volatility in Live Calf, Live Sheep, and Feed Wheat Return Markets: A Threat to Food Price Stability in Turkey. Agriculture 12(4): 566. https://doi.org/10.3390/agriculture12040566