Given that I bought a certain amount of BTC at a given point in time. Is there a way on cryptowat.ch or an equivalent platform, to mark the price and point of time at which I bought the BTCs and get information about how the current price is to the reference price in percent (preferably live)?
Not the way you are putting it but i update my portfolio on https://www.worldcoinindex.com/portfolio
This allows me to see in euro/usd and others. For example you bought 1000 usd of any combination of currencies. This profile wil tell you what it's worth approx (different markets have slight changes between them).
Added on 18.01.2017. See Changelog