# -110/-110 market implied sum = 1.0476 overround = 0.0476 # 4.76% hold = 0.0476 / 1.0476 = 4.55% # of balanced handle
On two-way markets vig and hold are near-interchangeable in casual use; the distinction matters on multi-way markets, where hold correctly expresses the margin as a share of all money wagered. Industry reports also use “hold” for a book's realized win percentage over a period, which mixes margin with luck.
With all books' prices in one response, per-book hold comparisons fall out of the feed for free. Low-hold books tend to be the sharp books whose prices are the best public proxy for fair value - the reason they get used as the devig anchor.