Many fibonacci levels are pointing to the high $20 levels into $22 as the next key resistance levels. The previous support and resistance that $20 has encountered has been very light. The chart below shows us that more acknowledgeable levels is $21.00 to the upside and the range of $19.50 to $19.75 going below. The $19.50/75 level recently has been massive which has given this level much more validity than $20.00.
In the 1979/1980 time frame $20 was small term support and resistance only. On the 1979 chart it was a small level of resistance that blew past on the second attempt. Thus this level was not that big. The second chart almost one year later the $20 level was an area of support only tested once that became resistance only tested once. For me to justify a historical level for this to be a relevant number I have to see it play more out as a key level. I would need to see it be a trading range as support/middle/resistance or be levels that is tested more frequently.
However, because many people see this as a psychological number, then this may cause a little bit of selling because its at area where it seems to be up too much on the short run. This can also cause a small buying surge as it is breaking $20. If it does manage to get past the $20, then the $21 area should be that key area where resistance is met and some selling would follow that may bring it back even towards the $19.00 area. I would be a little weary that this move to $20.00 maybe become a bull trap or a failed move on the short term, which could bring that fast move to the $18.75 area which is the next key support level on a decent size sell off. If that does not happen, then $21 will be the next target where probability odds are big for resistance to be met and held for at least a week or two. Just because probability odds say it will happen, does not make it so. For if you are 80% sure one situation may happen and the 80% guess/estimate has validity, then one of five times you will be wrong. Therefore if you play the $21 for a short term short scalp, then make sure you place a stop at an area you are comfortable with for the trade.