It is a statistical trap.
Don't let the yield ratio blind your eye. As many answers already pointed out, the yield ratio is based on the mandatory convertible warrant issuance price.
Mandatory convertibles bonds/warrants is a bet on futures and funding the company debt without burdens it with real payout when the bonds/warrant matures.
The DE000A189FZ7 statement says:
- The Minimum Conversion Price is adjusted to EUR 80.1522
- the Maximum Conversion Price is adjusted to EUR 96.1827
And you can just ignore complicated jargon and the wiki explain it clearly
Note that if the stock price is below the first conversion price the
investor would suffer a capital loss compared to its original
investment (excluding potential coupon payments). Mandatory
convertibles can be compared to forward selling of equity at a
Currently, the stock is trading around EUR 69.50. The bond par value 100 and the interest rate is 5.65%. When the bond matured, the investor will get EUR 5.65 but forced to convert with a price of EUR 80.1522.
Say in 2 months, the stock is going up to EUR75, people who bought the bond today (~EUR 81, ) will get EUR 5.65 and the equivalent stock, thus EUR 75 + 5.65. It looks like a breakeven.
But here is the catch: since BayerAG is price ~EUR69.50 today, for the same EUR75 projection, you can buy 15.7% more stock than buying the mandatory convertible. This means when the stock reach rises from EUR 69.50 to EUR 75, buying the stock will give you 6.49% returns.
p/s: nevertheless, whoever hold the convertible bonds can always declare it as loses for the tax credit.