How a round number like 100 works on a SOL perp

[Current events] A round-number level is a price where many traders place stops and liquidation buffers at the same time. For SOL this week that number is 100, and the BYDFi SOLUSDT page shows price has already dipped under it once.

The image is BYDFi's live SOLUSDT perpetual page at about 10:30 AM ET: last 101.30 (-0.27%), index 101.36, fair price 101.33, funding +0.0100% with 1:29:47 left, 24h high 102.21, 24h low 99.85, 24h volume 3.065M SOL, 309.881M USDT turnover and 10.550M USDT open interest. The 15 minute chart marks the 99.85 low.

The event

CoinDesk reported SOL fell about 2% in Monday's Asian session, "barely holding" 100, as crypto traders cut risk before Wednesday's Fed decision. BTC slipped under 80,000, ETH fell to just above 2,300, XRP dropped about 3% to 1.28 and BNB lost 1-2%. Crypto.com's weekend preview had SOL inside a 100 to 109 range after a sell-the-news reaction to the Alpenglow upgrade going live. Thursday adds the ECB, Friday the BoJ and a large monthly BTC options expiry.

Before: the stop most people use

• Long at 101.30, stop at an even 100.00
• Distance: 1.30, or 1.28%
• Problem: the 24h low was 99.85. A stop at exactly 100 would have been hit today, and so would every other stop parked at the round number. When many trigger together they can push price further for a moment.

After: a stop sized from the data

Worked example with a 2,000 USDT account risking 1% (20 USDT):

• Stop at 99.50, below both 100 and the 99.85 low: distance 1.80
• Position size: 20 / 1.80 = 11.11 SOL
• Notional: 11.11 x 101.30 = about 1,125.44 USDT
• Margin at 10x: about 112.54 USDT
• Rough 10x liquidation for an isolated long: 101.30 x 0.9 = about 91.17, far below the stop, so the stop does the work, not the liquidation engine

The wider stop means a smaller position. That is the trade-off: same 20 USDT risk, but fewer coins.

Fair price vs last price

BYDFi's header shows a fair price (101.33) next to the last price (101.30). On perps, liquidation is generally checked against a mark or fair price anchored to the index, not the last trade, so a brief wick to 99.85 does not move it as much. Stop orders are often triggered by last price, which is why a stop sitting on a round number can fire on a wick that never threatens your liquidation price.

Quick FAQ

Is 100 support? It is a level many traders watch; the chart only shows it was tested and broken intraday, not what happens next. Does funding matter here? At +0.0100% per 8h, the 1,125.44 USDT long above pays about 0.11 USDT per settlement. Small, but it adds up over a three-central-bank week. Why not just use higher leverage? It does not change the 20 USDT risk if the stop is fixed. It only moves your liquidation closer to the stop.