The last week of April will be extremely busy for markets with a third of the S&P 500 reporting earnings, a Federal Reserve meeting, and new spending and tax proposals from the White House.Big Tech is a highlight of the earnings calendar, with Apple, Microsoft, Amazon, Facebook and Alphabet all releasing results.The Fed is not expected to take any action, but economists expect it to defend its policy to let inflation run hot.There is some key data including first-quarter gross domestic product a