Amex is running a very short transfer bonus for Member Week to Marriott Bonvoy. Unfortunately, it’s not a very compelling offer, despite the short timeframe.
For one, an Amex point is worth around 2.5X a Marriott Bonvoy point. So you are getting 25% more while you’d need a 150% bonus to breakeven on point value.
For another, we have seen various transfer bonuses from Chase and American Express to Marriott Bonvoy many times before, racing from 20%-50%, so this is not even at the high end of the range. So this bonus isn’t going to be compelling for most.
As always, there can be exceptions and you might find a 5 night stay (5th night free) where the transfer makes sense, so do the math – but you likely do not want to transfer speculatively unless you are a Bonvoy pro and believe you will exceed value you can get via other, higher value, partners.