Market

Period. “Day”: the item's latest price is compared with yesterday's (recorded no later than 20 hours before it). “Week” and “Month”: the item's first price inside the period is compared with the latest. “All time”: with the very first price. Each item's own price records are counted, not dates: a collection can be incomplete, and an item's price may not have been recorded at all on some night. Items cheaper than 100 ₽ (by the higher of the two prices) and those with fewer than 10 sales a day are dropped: for a penny item a one-ruble shift gives +30%, and that says nothing about the market.

There's deliberately no single «biggest movers» list: growth in percent is unbounded, while a fall can't be steeper than −100%, and in one list the risers push the fallers out entirely.

Median of sales, only items with sales. The median is compared, that is the price the item was actually bought at, and only for items that sell. The cheapest listing of an item with no sales jumps with every random listing: that is how the table once showed «2.51 → 11 000, +438 147%» at zero sales. That was not a market move.