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.
Think of an auction. The bid is the price closest to the last transaction that buyers are willing to buy at. The ask is the price closest to the last transaction that sellers are willing to sell at. You can also think of them as the market price of a stock--bid being the market price if you are selling at the market and ask being the price if you are buying at the market. The difference between the bid price and the ask price is called the spread.. It is a fee that the market maker pockets as payment for keeping the market liquid. Generally, you will only see bid and ask prices quoted for NASDAQ stocks. On the NY and American exchanges the spread is a more uniform 1/16 to 1/8 point.