TOKYO (Reuters) - Shares of Sony Corp tumbled as much as 10 percent to a five-month low of 1,690 yen on Friday morning after it slashed its full-year operating profit forecast by 26 percent as its struggling TV operation fell back into red. The consumer electronics firm posted a net loss for the September quarter and cut its operating profit estimate for the year ending March 2014 to 170 billion yen ($1.73 billion) from 260 billion yen. By contrast, Panasonic Corp raised its earnings forecast on strong sales of products like batteries to industry clients, while Sharp Corp bounced to its first quarterly net profit in two years, helped by sales of solar panels. Panasonic climbed as much as 6.4 percent to a near 2-1/2 year high of 1,048 yen, while Sharp advanced 1.7 percent to 294 yen. ($1 = 98.1100 Japanese yen) (Reporting by Dominic Lau; Editing by Richard Pullin)