A per-keyword metric (used in Sellerize's tooling) measuring the percentage of a niche's total sales for that keyword that are captured by sellers outside the top 3 ranked listings.
High market availability (e.g. ≥40%) signals the niche isn't fully locked up by the top 3 — there's real sales volume for a new entrant to capture. Low availability means the top 3 sellers dominate the keyword's sales almost entirely, so ranking on page 1 for it wouldn't translate into much actual revenue for a new listing. Used alongside CPR (Units to Rank) Metric and conversion rate as one of the three axes in the High-Conversion Keyword Selection Strategy.
Roughly 70%+ market availability on a keyword is treated as a green light, since a new listing isn't going to land in the top 3 organic spots at launch anyway — high availability means there's still a large pool of sales happening outside the top 3 to capture. Availability around 10% is a red flag: the top sellers already absorb nearly all the demand, leaving little room for a new entrant regardless of listing quality.
A high Market Availability percentage for a keyword is a green flag, not a red flag: it means the top 3 incumbent listings are NOT monopolizing the niche's sales for that term, leaving room for a new listing to take share. Read it as "how much of this keyword's demand is up for grabs," not as a sign the keyword is undesirable.