Investors caught in crossfire of fight for holiday shoppers

NEW YORK (Reuters) - Investors would normally be thankful for a strong U.S. economy, yet this holiday season they worry retailers may have to spend heavily to win, leaving shareholders with a lump of coal.Steep discounts are as familiar a sight during the holidays as rich desserts, but this year so is a fierce grab for a slice of the e-commerce market as Amazon.com Inc and Target Corp offer free shipping for small purchases.Underwhelming earnings reports this week from Target to department..