But the market reaction and the plunge in the pound in reaction to a budget (and a mini one, at that) is seemingly unprecedented. Experienced financial commentators saying they've never seen anything like it. A mini budget became a self-inflicted financial crisis.
What
@Seanm said, basically. Markets are gonna market. An adverse market reaction is not
in itself evidence of poor economic policy. Two recent examples...
Firstly, the fear of an adverse market reaction (along with with the loss of AAA credit rating) was used to motivate austerity, one of the most disastrous economic decisions ever taken in the UK (of course, it was really a political decision). Looking back, I'd take the adverse reaction of the markets and use economic policy to help people in need.
Secondly, the markets would probably have reacted badly to a John McDonnell budget that promised huge investment in infrastructure and a green new deal, even though those policies are exactly what the UK needs (other opinions available).
As for the mini-budget itself, the Torsten Bell thread Sean linked to is useful. From the point of view of the average voter, it offers a lot of help with fuel bills, and tax/NI cuts to further sweeten the deal. I don't see how this can be unpopular, and I doubt that people will care much about how the market reacts, or how the whole thing is "paid for".
Bell also makes clear that Kwarteng hasn't abandoned Treasury orthodoxy and commits to reducing debt as a proportion of GDP in the medium term. There is also a commitment to publish an OBR forecast by the end of the year. Bell sees both of these as good things but I'm not so sure - I mean, it's not as if Treasury orthodoxy has brought the UK to a good place economically, so far, is it?
I think the mini-budget is also correct to identify poor growth as a key issue but the easiest fix for that is to put money in the pockets of people who are not well off, not those who are already wealthy. Thus, the abolition of the top rate of tax is, by far, the worst aspect of the budget, as far as I'm concerned. It's hard to see it as anything other than a naked expression of class loyalty.
Overall, a curate's egg, but
it's not as if Labour are offering anything better so... shrugs.