* Nikkei shed 3 pct to 4-month closing low * Nikkei has lost 16 pct from a one-year peak on March 27 * Financials suffer on fears of Europe contagion * Komatsu, HCM sink after Caterpillar sales fall in April By Dominic Lau TOKYO, May 18 (Reuters) - Japan's Nikkei average shed 3 percent on Friday to log a seventh straight week of losses, its longest such run since the third quarter of 2001, as investors sold stocks and other risky assets on concerns over slowing global growth and a deepening euro zone crisis. The Nikkei fell 265.28 points to 8,611.31, taking its decline to 16 percent since hitting a one-year high on March 27.