Sharecast - The target price on the ‘underweight’ rated stock was cut to 220p from 230p.
Kingfisher (LON:KGF) is scheduled to report H1 24 results on 19 September.
JPM said: "Whilst data for UK and French home improvement has remained strong, both countries slowed in July, and housing markets have softened.
"Combined with our view that we could see more promotional behaviour from competitor Leroy Merlin (as it targets regaining share) we continue to see downside risk to forecasts (we sit 5%/ 9% below FY 24 / FY 25E profit before tax consensus) and therefore place the stock on negative catalyst watch."
JPM said its multiples-based target price was cut to reflect changes to its forecasts.
The bank expects Q2 group like-for-like sales down 3.6% year-on-year, and H1 24 pre-tax profit of £355m, in line with guidance for £350m.
At 0850 BST, the shares were down 1.1% at 234.10p.