This all goes back to pre-cessation triggers. The FCA can at any point announce that they consider that as of a certain date in the future that LIBOR (for a certain currency and tenor) is no longer representative. At the point it makes that announcement the clock stops on the 5 year lookback period – i.e. the spread adjustment will be calculated as the median of LIBOR/RFR basis for the 5 year period up until the announcement date. The spread adjustment will then be fixed as ‘X’, and that number used when cessation finally occurs...which might be a week or a year later (though not before January 2022).
And the noises from the official sector seem to indicate increasingly that this might be more like a year in advance....ie the FCA might say in December 2020 that it expects LIBOR to be non-representative from 3 January 2022. The 5 year period for fixing the adjustment spread would then be December 2015 to December 2020.
We think it is possible the initial success (or otherwise) of the protocol, and greater clarity on tough legacy, might be influencing factors on whether the FCA make such an announcement early. The thinking being that an early announcement and a long lead in will give the market certainty on pricing and timing, and drive forward the pace of transition.
See the diagram below for an illustration of how the timings might work: