Impulse waves almost always correct in wave 4 territory. If you look closely at the chart, you can see wave 5 was definitely an extended wave. This means wave 4 was very low relative to the impulse move. Looking back, it should not have come as this much of a shock had I known about Elliott waves. Fibonacci retracement indicated a higher correction but Elliott wave theory was the key to understanding the correction.
Comment:
Additionally, the huge converging triangle was also a potent indicator of the dump (not shown)