This has all happened before, it will all happen again.
There will be a time to position for long entries, but it will take some time (aside from intraday short covering rallies).
I use the 3/10macd indicator because it is closely derived from price and reacts quickly to price; all it does for me is help to take out some of the noise and subjectivity in viewing price.  The criteria I ascribe to the indicator's relationship of Fast Line to Slow Line is simply my way to quickly identify, and alert me to, higher lows or higher highs, trend continuation likelihood, range-bound markets, etc.
With that said, the 2b, 4c, or 4b criteria simply alerts me to a lower high or waning momentum.  In the chart below there's a 4c and 4b short setup highlighted:

or even this 4c criteria on the monthly S&P500 chart:

And more recently, this:

as an added bonus, the 2b criteria on the 3/10 macd isn't necessarily a lower high.  In the chart above the absolute high (prior to the shaded region) occurred while signaling a 2b setup (exhaustion of price/waning momentum).

Anyway, as we can see from the above chart, price confirmed a lower high and sold off.  At this point, the rallies will get sold and we will likely spend a number of weeks digesting the recent volatility to a point where a firm higher low can develop and begin a new intermediate trend up.  The question always remains; How low will we go?

To start with, take a look at this morning's opening gap down.  Price reached the 100% projection intra-day, while the 200% coincides with the August 9 lows.  Not to say price always achieves a 200% momentum projection, but the fact that it coincides with the lows is curious

tough action

 First trade was in GS and I felt it was a decent enough trade as my target was only $0.50 and the concept of momentum, pullback, continuation was legitimate enough.  The 5-min chart on the right indicates the entry and my target for half the position was vwap (not on the chart).  So, on getting my half position filled, I exited a bit below my original entry on the other half on the basis that the Open price was rejected and the sector itself was weak.

I was watching ANR and MEE as 3d-criteria setups going into the day (triggered at the close yesterday), so I was looking to buy a pullback, but instead I should have been looking to short a pullback after previous resistance was unable to hold support.  Not sure why I didn't reverse to go short on this failed long trade, as I find that if the 3d setup doesn't follow-through it's not uncommon for it to roll over and go lower (when the Fast Line & Slow Line cross on the 15-min chart).

Here was a better 3d setup that I wish I would have seen.  Much cleaner and easier to define targets as well as see price fail resistance and roll-over:

Finally, FCX was a good trade, good setup, but my position size was small.  To reiterate, the criteria I ascribe to the 3/10 macd is only a method for me to define a stage that price is in.  "4c" is a good probability bear flag, the 3/10 macd just helps to put a filter on noisy price behavior.
I made an error in labeling this chart; where it says "out" with the up arrow on the 5-min chart was for half the position, the second half was exited when price returned to the 50% extension at $52.36.

shorts mostly

FCX
  Reverse divergence short (higher time frame failed pennant breakout) on the bearish engulfing candle (6th bar) on the 15-min bar.  Cover on the momentum div.   Short again on the 2d criteria setup cover end of day

GS inverted cup w. handle breakdown corresponding with a 4d short setup.

JCP long based on a 3d setup.  With this much weakness my initial target for half was the PDL, while the other half was stopped out at b/e.  Always look to reverse when the 3d pattern fails.

AMZN ascending triangle breakout (3a long entry) turned fakeout.  Was a nice bear flag pattern into the close but I didn't revisit

missed opportunity

Some setups I saw today but didn't take and one that I did.
RVBD 3d setup, long on an opening range breakout

RIMM; nothing stellar, but it worked, 3a criteria on the 15-min chart waiting for a pullback on the 5-min chart which coincided with an ascending triangle breakout.

PAY, 3d setup ascending triangle. nice how breakout resistance turned support.

X, I actually took this trade but hesitated for 10-minutes.  It was another 3d entry but the entry candle should have been two bars earlier (on the 5-min chart) but I didn't trust it.  Exited at $53.90 because of longer-term resistance at the $54 whole number.