I see that many people here don't understand the core ideas behind Stellar/Lumens.
Calling it pre-mined when there is no actual mining going on and smilier misunderstandings.
I wrote an overview of Stellar if someone is interested in learning more about it:
https://galactictalk.org/d/1-start-here-everything-you-need-to-know-about-stellarRegarding the price of Lumens. When the Bitcoin giveaway was announced the price already adjusted. I think it was a 20% drop.
Many people will not claim the Bitcoin reward and many Bitcoins are already lost (Satoshi's coins). So you should worry more about the October giveaway:
https://www.stellar.org/blog/build-challenge/And I think Jed said somewhere this will be the coins not claimed now. So Stellar.org is only expecting 1B to get to users now.
Usually the trading volume is not too high for Lumens, but if you look at last week it exploded and the price increased again 20%.
Obviously someone was buying a big amount until exhausting the "cheap" supply.
With such love liquidity it's impossible to predict how the price will behave in the future.
Also note that Stripe bought 2 billion Lumens for 2 million USD:
https://stripe.com/blog/stellarWhat results in a price of $0.0015 per Lumen. If you look at the last 6 months you will see that the price was always fluctuating a bit above this value.
So please check everything before trading Lumens. You don't want to end up in a margin short while some financial institution is buying a few millions.