RE: Musing Posts
That is controlled by the price feed and also the debt ratio of STEEM-SBD.
SBD is a debt issued token and the $1 peg ($1 of STEEM as per whitepaper) is only guaranteed up to 10% of debt ratio. When the STEEM price (feed) is low, like now, and in the months before much SBD has been printed to pay out rewards, then the debt ratio can increase very quickly because the price of SBD is pegged to the value of $1 of STEEM, yet the market value of STEEM goes down.
The Steem blockchain has a mechanism built-in which starts to reward out in also STEEM when the debt ratio increases and reaches certain levels. At some point, like now, that may result in being paid out only in STEEM. Currently this is being triggered at 2% debt ratio and from 2-5% debt the amount of rewards which are paid out in STEEM rather than in SBD linearly increases. If the debt ratio goes beyond 5% then no more SBD is printed but everyone is rewarded in STEEM.
And in vests (SP) too, of course.
With HF20 the debt ratio correction will kick in later than it does now and only be triggered at 9% debt.
Top 20 witness @timcliff has an excellent post about SBD and how it functions.