Willy has been buying 10-20 Bitcoins every 5-10 minutes and therefore shifting the balance of supply and demand towards demand drastically.
https://willyreport.wordpress.com/2014/05/25/the-willy-report-proof-of-massive-fraudulent-trading-activity-at-mt-gox-and-how-it-has-affected-the-price-of-bitcoin/
To simplify lets take 20 Bitcoins every 10 minutes as average.
The Halving will subtract 12.5 Bitcoins every 10 minutes in average from the supply.
Comparing those two one can easily see the impact that the Halving will have on the price of Bitcoin, not as strong as Willy but very effective and completely legal.
Demand since willy has doubled and by halving will have tripled, so impact will be better far more than Willy. If Willy alone took us to $1200, halving will be 10X that.
