Deconstructing the 2017 Changes to AWS Spot Market Pricing

The Amazon Web Services spot market sells excess computing capacity at a reduced price and with reduced reliability guarantees. The low cost nature of the spot market has led to widespread adoption in industry and science. However, one of the challenges with using the spot market is that it is intentionally opaque and thus users have little understanding of the underlying dynamics. In late 2017, the mechanisms underlying the spot market were significantly altered-no longer are bid prices used to clear capacity and as a result the pricing is much less volatile. In this paper, we revisit prior work with the aim to analyze the differences in market dynamics between the pre-change and post-change spot instance market. We then use these analyses to highlight possible properties of the current and previous pricing algorithms, including artificial manipulation, dynamic algorithm adjustment, and persistent trends in market supply, demand, and pricing.