PTS Deflationary effect.
There is a chart showing the reduction of supply -
http://pts.bitsharesblocks.com/supplyWhile bitcoin (approx 10% inflation) and most altcoins go inflationary, PTS is going the opposite direction. A deflationary PTS helps to preserves your PTS investment for the long term and keep the price stable.

This doesn't seem to be reflected in Coinmarketcap supply, which shows 999,999,386 PTS currently.