lets say,I have 2 BTC over some exchange, presently bitcoin price is 2000$ , so basically i have 4000$, now the price of bitcoin fell to 1000$ , so the total value is 2000$. Is there any way so that i can convert the 2 btc at the time when btc wad 2000$ to usd, and when it goes back cheap i buy it with the usd at the exchange?
I herd someone told me yes, if yes then please let me know the exchange which support such thing. i have been trading BTC since old time but never came across that we can even trade usd with BTC as a pair.
Pegged cryptocurrencies can still fluctuate in value a lot depending on the method by which they are pegged to the fiat currency. For example Steem dollars is currently at $1.2+ apiece and it is supposed to be worth $1. Tether was at around $0.96 before because of the Bitfinex withdrawals fiasco. But now it's risen again. I suggest using Wirex or Xapo, both of which have "hedged accounts" where you can hold USD directly, and exchange rates aren't that bad.
If you are looking for a mobile wallet try mobi, you can even hold gold and silver.