Yes I would suggest anyone who is panicking reads the H1 2019...

Yes I would suggest anyone who is panicking reads the H1 2019 presentation. A few key points:
1) Webjet has recently in April reaffirmed guidance for 120mill ebitda which is ~50% growth on fy2018
2) they also guided for at least an additional 40mill ebitda growth in next FY ie fy19-20 which is at least 33% growth and likely a conservative estimate.
3) as correctly pointed out above they haven’t yet recognised any Thomas cook revenue as the plan is for this to kick in June 1. The forecast TC b2b revenue is with minimal cost such that most was guided to flow through to ebitda. If TC declines majorly, this will have a modest impact on fy19-20 forecast ebitda growth but how much? Well given they guided for 300m as a conservative ttv which at an 8% ttv/ revenue ratio to 24m revenue and at a 5/3 rev/ ebitda ratio is around 14-15m ebitda. So even if bookings dropped catastrophically by half this would be a 7m drop in group ebitda at constant ratios, so downward revision of 7/160 = a 4% downward revision to group ebitda for fy 19/20, which is still ebitda growth from 120 to 153m ie 25+% growth.
i am of the opinion that the forward guidance has been deliberately conservative from management and the board given the unstable global geopolitical and economic environment, so any Thomas cook downward revisions could easily be offset by outperformance of Jac travel, dotw, Webjet etc.

the company - in their h1 results presentation - also restated their goal to expand their ttv/ ebitda margin from 8/3 up to 8/4 by fy 2022. This would obviously expand ebitda by 33% so for example if 2021 ebitda is 160m and fy22 is a conservative 190m (sub 20% growth) then a 33% margin expansion would expand ebitda to 250mill.
that would mean the current market cap values Webjet at 8x FYI 22 ebitda which is fairly conservative for a stock which a long growth runway ahead.

the point of all these numbers is to demonstrate that the growth and thus valuation of Webjet is not going to be derailed by the TC woes. Even if TC went completely bankrupt it would only have a maximum 10% impact on fy19-20 ebitda and likely less than that. So yes it is material but not a big deal. If the share price dropped another 10% to $14 it would be a great medium term buying opportunity. At 15.50 it is undervalued but not by enough to enter my buy zone. I would value Webjet at around $18-19 but I wouldn’t add to my holdings above 14.00 given my average buy price is around 8.00.