
Once the bottom of 1998 occurred, it took 2 years before the market adjusted its rapid rise to a more appropriate amount of time as can be seen by the fibonacci arc on the chart above. This arc helps measure the relationship between price and time. However, even then (once the initial thrust occurred) the market never again reached the top arc, which is contrary to what is occurring below.
Notice as well that simple trendlines could have been used to help tell when the bubble was over. The 3 black trendlines could have helped investors know when the environment was changing and allowed for consolidation of gains depending on their timeframes (short, mid, longterm).
While the general stock market indices today are not yet at parabolic rises, certain darling stocks, are. When prices go vertical, there is reason to notice and a HUGE warning sign should be the result. Assuming 90 degrees is vertical, stock prices physically cannot move more than 90 degrees in time (that would be going back in time), and there needs to be a balance between price and time as time value of money, changing environments, profit taking, etc will eventually catch up to rising euphoria.
On the chart below I show Apple's recent price action...this does not look healthy and is cause for major concern. The stock is well over an 80 degree angle and well beyond any of the standard moving averages. It is tough to find another stock rising at such a rapid pace (CMG and CRM are examples). Using the longer term (pink) trendline, a pullback to $400 does not seem out of question. Similarly, shorter term trendlines can be used at different time frames to help show when the environment has changed.

The chart is pretty busy, but the 3 points at the top of it summarizes...
1) The rise from the 2009 low, was a lot more healthy than the current rise as support was found twice by the fibo arc.
2) The long term trendline sits around $400...I fully expect this trendline to be found again (likely sooner than later).
3) The latest rally can pretty much be classified as parabolic...price should fall hard to at least the middle fibonacci arc once 1-2 of the black trendlines break.
Although, it has yet to occur, I fully expect Apple to come back to earth. I will watch the black trendlines to help show me when that will occur.
Good luck!