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.
The Bid/Ask Spread. The bid/ask spread is the difference in price between the bid and ask. In active stocks the bid/ask spread is typically $0.01, for example the bid is $10.05 and the offer is $10.06. The attached chart example shows a Level 2 in the SPDR S&P 500 ETF.