Hello proname,
This is a good question, as the price of USDT cannot deviate greatly from the value of the dollar. The reason why the price is near this constant is because it is linked to the value of the dollar. This means that the dollar can decline in value, but 1 USD Tether, will always be worth around 1 US dollar. There are several concerns whether trading pairs like these can be used to influence the price of Bitcoin.
As stated in the whitepaper of tether each tether that is issued into circulation is backed in a one-to-one ratio with the equivalent amount of corresponding fiat currency held in reserves by Tether Limited. They also state that whenever a user deposits tethers with Thether Limited, in order to redeem them into fiat currency, that Tether Limited destroys the tethers that were redeemed and that they send the fiat currency to the users bank account.
Because of the way tethers currently work, there are suspicions that the currency is being used to artificially influence the price of Bitcoin. An article that goes in to depth in regards to these accusations can be found
here.With kind regards,
The Anycoin Direct team