Can someone please explain to me how you can just go on a spending spree and spend $21 Billion in under a month with no one going: 'Hey, umm guys, I know we re

Can someone please explain to me how you can just go on a spending spree and spend $21 Billion in under a month with no one going: 'Hey, umm guys, I know we really like the company, but lets have things cool down a bit after spend 19 billion.' In the Whatsapp acquisition thread someone made a comment about FB thinking their stock valuation is overpriced. I'm curious to hear what the split (cash/stock) is. If it's stock heavy, I'm almost certain that person was right.