So, let's get clear what we're talking about: Blood moons are lunar eclipses. Occasionally the sky shows us a tetrad (a series of 4 consecutive total eclipses occurring at approximately six month intervals, per NASA). It is alleged that these events (Tetrads) are "prophetically significant" and have served as prophetic signs and warnings about important days in Jewish history, for example the expulsion of the Jews from Spain in 1492, the founding of modern Israel in 1948, and the six day war in 1967. Tetrads are big in BMS theory.

Then there's the Shemitah – the debt "release" commanded of Israel (found in Leviticus 25) which she was to observe on a 7 year cycle. According to the Bible the Shemitah system was turned from a blessing to a curse when Israel ignored it. According to BMS theory, this applies not just to ancient Israel, but to modern America, and Shemitah years have coincided with stock market collapses. In fact, they tell us that 8 of the 10 largest market collapse in the past 100 years have occurred on Shemitah years. Furthermore, we're told that Shemitah years also correspond with important dates in Israel's history, for example, the beginning of the Holocaust. Shemitah years are also big in BMS theory.

But now we've got a tetrad and (allegedly) a Shemitah year at the same time! A great convergence of great signs pointing towards an extremely important prophetic season, and we are warned of a great likelihood of market collapse; a big one on September 28th (the last of the tetrads) and a smaller one this Saturday (the third eclipse of the tetrad). Rabbi Cahn, in particular, has cautioned people to be out of the stock market at this time.

Scary stuff. But is it true?

Not really.

Let's fact-check it:

First, Tetrads have not actually generally served as warning signs in advance of major events in Jewish history. In fact, none of the four tetrads of the first millennium coincided with important dates in Jewish history. Furthermore the most important events in that time period all happened during non-tetrad years: Neither the birth of the Messiah, nor His death and resurrection, nor the destruction of the temple, nor the destruction of the entire nation occurred during a tetrad.

Second, although there are a few events which have been in the historical vicinity of Tetrads (such as the expulsion of the Jews from Spain, the founding of Israel, and the Six Day War) these signs and warnings generally occurred after the tetrad. Furthermore, in many of those cases, the eclipses were not visible from Israel (or in the case of the expulsion, not visible from Spain either). It's hard to square BMS theory about tetrads as warnings if the warnings mostly occur after the event, and were not visible to the people being warned.

Third, when Rabbi Cahn tells his readers that 8 out of 10 of the largest market corrections in the past century occurred during these alleged Shemitah years, he does not mention that 5 of the 8 occurred in 2008, nor that the remaining 3 occurred in 2001. Confused? Cahn uses the dollar value declines, rather than (the appropriate) percentage decline. If he had calculated corrections the way pretty much everybody else does, he would have found that the crash of 1929, was by the far the largest correction, and that it did not occur on a Shemitah year. In fact, a majority of the top ten percentage market crashes occurred on non-alleged Shemitah years.

Fourth, I've used the word "alleged" about the Shemitah years, and you need to know why: No one actually knows for sure which years are actually Shemitah years. The Torah doesn't give us dates for them, so there is no way to know with certainty whether 2014-2015 actually qualifies biblically. Instead BMS advocates end up having to choose one or another competing particular rabbinical traditions. Tradition, not Bible, not proof.

Fifth, even if BMS advocates have somehow chosen the right year to initiate their Shemitah calculations, that their view of this current year being a Shemitah must be wrong. That's because the only way to get 1903 and 2015 to both qualify, is to omit the Jubilee year. You can't just start in a certain year and then add 7 forever. Once every 50 years, you have to add one. They don't.

Sixth, if one is going to use the Hebrew calendar to choose the year, one should also use the Hebrew calendar year to choose the months. The claim that Kristallnacht, which initiated the Holocaust, began in an alleged Shemitah year depends on using the Hebrew calendar to choose 1938, but then switching to a Gregorian calendar to fit Kristallnacht in. If this system runs on Hebrew calendrics, why the switch?

Seventh, everything else. There are numerous other problems – historical, astronomical, et cetera – with the BMS view, far more than we can deal with in this space. For more detail, please consult the much more detailed White Paper on this issue, which I helped write.

BMS advocates look at the world through an open Bible. That's good. But it's not enough. One of the authors has said publicly that he wrote this book in six weeks. Kudos for work ethic, but not for fact-checking. Accuracy takers time, so it falls upon us to check things out for ourselves. And when we do, the theory just does not hold up.

I'm afraid that we're going to have to keep doing the hard work of financial and economic analysis to make investment decisions, instead of relying on blood moons. Sorry it didn't work. It was a cool idea.