Cardiac tamponade can occur due to: 1  Dissecting aortic aneurysm (thoracic) 2  End-stage lung cancer. 3  Heart attack (acute MI) 4  Heart surgery. 5  Pericarditis caused by bacterial or viral infections. 6  Wounds to the heart.
Bid vs. ask and why yields matter. With many investments, the concept of bid and ask applies to prices. The bid price is what a buyer is willing to pay for a security, while the ask price is what a seller is willing to accept for the same security. The difference between those two numbers is known as the bid-ask spread, and in general, the narrower that spread, the more liquid the market is.
Working the Option Market Maker's Bid/Ask Spread. The bid/ask pricing on an equity, index or ETF option can vary from a couple cents to a couple dollars these days. In general, bid/ask spreads are narrower than in the past due to multiple exchanges, the prominence of electronic trading and market makers competing for retail option order flow.