Altcoin season index

The line is the altcoin season index, one reading a day on a scale from 0 to 100: the share of the largest coins, up to a hundred of them, that did better than bitcoin over the ninety days before that day. At 100 every one of them beat bitcoin; at 0 none did.

From 75 up the chart tints the ground green, altcoin season; from 25 down it tints it orange, bitcoin season; between the dashed lines is neither. The scale on the right names the three and lights the one the latest reading stands in. The readout above gives the latest reading and those of yesterday, last week and last month; under the plot are the highest and lowest readings of the last year, or of the whole record while it is younger than that, and, when the day's market data is to hand, the same count taken over a day, a week, a month and a year.

Hovering any day gives its reading, its season and the date. While the record is young the chips cut it to three or six months.

Each day Perly takes the largest coins by that day's market capitalisation, up to a hundred of them, leaving out stablecoins and other coins whose price barely moves, wrapped, staked and bridged versions of other coins, and coins that simply track bitcoin. For each it compares the price change over the previous ninety days with bitcoin's, and the index is the share of them that did better. The record follows about the 120 largest coins, so once stablecoins and the rest are left out a day's field can hold fewer than a hundred; a day with fewer than forty coins to compare is left out rather than called on too few.

The field is each day's own, so a coin counts on the days it was among the largest and not before or after. The record is Perly's own, kept daily from CoinGecko's prices and market caps for the largest coins. Its first year was filled in from that free history, as far back as it goes, and the index starts ninety days into it; the note under the chart gives the day the record begins.

The original, Blockchain Center's, counts the top 50 coins over the same ninety days and calls altcoin season at the same 75. Perly's field is up to a hundred coins, so it reaches further down the market, and the index is computed from Perly's own record rather than copied from anyone's. The two need not give the same number on the same day.

The record is still short, so the table's months are the whole of it. An index that counts winners over ninety days moves slowly and turns late, and a few more years of it will say more about what an ordinary range looks like than any threshold can.