I had the same guess. That Lisk can be used to buy Ark with a big bonus will definitely push the price more. The price has risen by around 15% today. The ICO starts soon. Lucky who bought somes days ago.
Already +30% from time when I bought more LSK. Is it still bullish movement from ARK?
I think also the price of BTC have affected Lisk. Now the BTC is steady risk may rise again. We might see 40 42k