MACD Crossover Below Zero Line Longterm

I updated the title of this question to better match the context of it’s description.

Here is the code to perform the scan as requested.

The Inputs:

There are two inputs to adjust how the crossover detection is handled. The lookbackPeriod is the length of time the two lines of the MACD should be crossed to the downside. This is the same as the Histogram being below zero line and thus the code uses this instead of testing the two lines. The other input is called barsBeforeCrossover and this tells how many bars before the crossover to look for the lowest price of the Value line.

How it Works:

The code compares this low to the lowest price of the Value line during the lookbackPeriod. This is a very simplistic approach. It does not detect if the two lines of the MACD had been in a steady decline throughout the lookbackPeriod. The default value of the lookbackPeriod is set to one year of daily bars. I imagine this condition is very rare.

The Scan:

The final statement at the end is testing for the signal having occurred a number of bars in the past. In this case, it is looking backward to see if the given conditions were present anytime within the last 30 bars. In order to get any signals to show up, I had to set the lookbackPeriod down to 60.

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Here is the code:

input fastLength = 12;
input slowLength = 26;
input MACDLength = 9;
input lookbackPeriod = 252;
input barsBeforeCrossover = 5;
input averageType = AverageType.EXPONENTIAL;
def Value = MovingAverage(averageType, close, fastLength) - MovingAverage(averageType, close, slowLength);
def Avg = MovingAverage(averageType, Value, MACDLength);
def Diff = Value - Avg;
def belowZeroForLookbackPeriod = Highest(Diff, lookbackPeriod) < 0;
def theCrossOver = Diff[1] < 0 and Diff > 0;
def lowBeforeCrossOver = if theCrossover then Lowest(Value, barsBeforeCrossover) else 0;
def crossoverLowIsLowestInLookbackPeriod = theCrossover and lowBeforeCrossover < Lowest(Value[barsBeforeCrossover], lookbackPeriod);
def signal = belowZeroForLookbackPeriod[1] and crossoverLowIsLowestInLookbackPeriod;
plot scan = Highest(signal, 30) > 0;

Pete, Sorry for the delay I have been traveling. I have been playing around with that code but it is not coming up with anything. In my scans I change the Fast/ Slow length to 15/30. Currently the stock MGM is doing this crossover as you can see from the attachment. For some reason this scan is not picking this up. Do you have any idea what can be changed to find tis. I do realize that this is a rare occurrence but it seems that A stock will usually do this once or twice per year.

Pete, Sorry for not providing the aggregation period. I currently have it set at a Daily Chart. In terms of the histogram moving above the zero line becoming invalid. I would omit that language.  As you can see from the MGM screenshot the histogram is above zero on more then one occasion. The anomaly that I find interesting is when the Fast is below the slow and the two of them are in that almost free fall over a period of time then you have that crossover that occurs when it bottoms out. I believe I sent you a PayPal for the premium??? I am not sure if I sent it correctly, please check.