Background: Vegetable price volatility poses a serious challenge to food security and agricultural sustainability, particularly in developing countries such as the Philippines. Fluctuations in prices disrupt market efficiency, reduce producer and consumer welfare, and hinder long-term planning in the agricultural sector. This study investigates the drivers of price volatility in two key condiment vegetables—onion and garlic—which are highly traded and politically sensitive commodities in the Philippines. Methods: Using quarterly data from 2010 to 2024, this study decomposes farm, wholesale, and retail price variances into demand, supply, and import components. A variance decomposition framework was employed, complemented by Monte Carlo simulations to test the robustness of elasticity estimates under data-scarce and uncertain conditions. Results: The findings reveal that demand volatility is the dominant driver of price fluctuations, explaining 50–90% of total price variance across markets, followed by supply shocks (9–50%), while the influence of imports is comparatively negligible, accounting for only 0–13%. Seasonal production patterns amplify these fluctuations, while the impact of import activity is understated due to unrecorded volumes from smuggling and illegal trade. The robustness of the decomposition estimates is validated through Monte Carlo simulations for onions, whereas the wider volatility observed in garlic reflects underlying structural production challenges and import dependency. Limitations include truncated retail-price data (2021–2021) and unrecorded smuggling volumes. Conclusion: The study underscores that domestic market dynamics—particularly demand and seasonal supply shifts—play a more statistically significant role in vegetable price instability than trade flows. Policy interventions should prioritize market modernization, investment in infrastructure, farmer capacity-building, and the strict enforcement of anti-smuggling laws. Strengthening existing agricultural legislation and aligning programs with the Philippine Vegetable Industry Roadmap are critical steps toward improving price stability and food security.

Purpose Achieving self-sufficiency in vegetable production is a critical issue in emerging economies, including the Philippines. Onions, a staple in Filipino dishes, have faced market instability owing to frequent price fluctuations. Understanding price transmission at various stages in the onion supply chain is essential for assessing market efficiency. Design/methodology/approach This study uses monthly price data from farmers, wholesalers and retailers. Three price transmission cases were examined: (1) wholesalers-farmers, (2) retailers-farmers and (3) retailers-wholesalers. Symmetric and asymmetric cases were analyzed using autoregressive distributed lag and nonlinear autoregressive distributed lag models. Findings The results show price symmetry between wholesalers and retailers but asymmetric price transmission from farmers to wholesalers and retailers. Retailers benefit from symmetric price signals owing to daily price-monitoring reports and government pricing policies. Farmers, constrained by onion perishability, are forced to sell to wholesalers who also serve as traders and financiers, accepting agreed-upon contract prices to avoid losses. Research limitations/implications This analysis focused on the national domestic prices of red onions, excluding import prices. Future research could expand on this by incorporating import prices into market efficiency analysis. Additionally, exploring spatial price dynamics at provincial and regional levels would provide further insights. Originality/value This study adds to limited research on asymmetric price transmission in the Philippine onion market. It provides insights for addressing market inefficiencies in developing countries and supports the United Nations’ “Zero Hunger” sustainable development goal, particularly in promoting sustainable agricultural production and food security.

As the furthermost popular measure of risk in many financial activities, recent developments such as initiation of new methodologies should be explored to keep up with the market dynamics. This study examines Philippine Stock and Foreign Exchange Market from 1 January 1987 through 1 January 2020. Modified iterated cumulative sum of squares (MICSS) algorithm is implemented to trace structural breaks in the variance. Local political events are blamed for stock market disruptions, but financial crises have an impact on foreign exchange markets. General autoregressive conditional heteroscedasticity (GARCH) model is then employed in estimating persistence in volatility and a framework to test for spillover effects (hypotheses of heat wave and meteor shower). Substantial drop of volatility persistence is seen in the model, once structural breaks are present. With respect to volatility dynamics, heat waves’ supremacy is observed for both markets.