Bitcoin Stock-to-Flow model review and its link to the 4‑year halving

Bitcoin’s Stock‑to‑Flow (S2F) valuation model, first published in March 2019, remains a focal point for analysts who tie its scarcity‑based price forecast to the cryptocurrency’s four‑year halving rhythm [1]. The model’s relevance hinges on whether market participants continue to price scarcity ahead of each halving, a question that shapes expectations for Bitcoin’s next price trajectory.

How the S2F model works

The S2F metric measures scarcity as the ratio of existing Bitcoin supply to the flow of newly minted coins (the inverse of the inflation rate). Using monthly data from October 2009 to February 2019, the model fits a power‑law curve: Price = 0.4 × S2F³ [1]. An alternative fit using annual data from 2009‑2019 yields Price = 0.18 × S2F³·³, projecting higher prices for the same S2F level. Proponents cite the model’s tight fit to historical price‑S2F data, while critics invoke the Efficient Market Hypothesis (EMH) to argue that any publicly known scarcity metric should already be reflected in price [1].

The four‑year halving cycle as context

Bitcoin’s supply schedule enforces a halving every ~210,000 blocks, roughly every four years, cutting block rewards by 50 % [2]. Each halving reduces the flow of new BTC, raising the S2F ratio and, under the S2F framework, should lift price. Historical halving events have been followed by all‑time highs within 12‑18 months, though the magnitude of gains has tapered as the asset matures [2]. This pattern supplies the “anchor” that S2F analysts use to justify future price targets, while EMH supporters point to the diminishing incremental impact of each halving as evidence that markets may already price the scarcity effect.

Market sentiment and on‑chain signals

Despite the theoretical appeal of S2F, real‑world arbitrage opportunities have faded. Early Bitcoin trading allowed cross‑exchange price differentials (e.g., BTC/USD = 8,100 vs. BTC/EUR = 7,300 on 13 Jan 2010) that could be exploited, but high‑frequency trading and tighter spreads have largely eliminated such gaps [1]. The current market, estimated at roughly $150 billion with about $10 billion in daily transaction volume, is considered “fairly efficient,” meaning new information—such as a halving‑driven supply shock—must be substantial to move price [1].

What to watch

• Next halving date – Expected around the 210,000‑block mark in 2024; price reactions often begin weeks before the event.
• S2F ratio movements – A rising S2F (higher scarcity) could reinforce bullish S2F forecasts if it outpaces market expectations.
• Derivatives positioning – Options and futures markets showing limited volatility around past halvings may signal muted expectations for a sharp price swing this cycle [1].

The ongoing debate between scarcity‑driven models like S2F and EMH‑based efficiency highlights a core tension: whether Bitcoin’s price will continue to climb in step with its programmed supply reductions, or whether the market has already baked in those reductions, leaving future moves to be driven by broader liquidity and sentiment factors. The answer will become clearer as the next halving approaches.