Source: Sharecast
In a brief update, the North Sea oil and gas producer - the UK’s largest - said it was making "good progress" on concluding both the prospectus and shareholder circular.
The documents were in the final stages of preparation, it noted, with publication likely "in the coming weeks".
The shareholder vote on the deal will then be held.
Harbour concluded: "All regulatory, anti-trust and foreign direct investment approvals required for completion continue to progress as planned, and Harbour continues to expect to complete the acquisition during the fourth quarter of 2024."
As at 0915 BST, shares in Harbour were up 1% at 324.9p.
Harbour agreed to acquire the much larger business in a share and cash deal with Germany’s BASF and investment firm LetterOne, Wintershall Dea’s owners, last December.
The blockbuster deal will transform Harbour from a UK-focused producer with a market value of around £2bn to a global player with projects across multiple countries.
The deal includes Wintershall’s oil and gas fields in Germany, Norway, Mexico and Egypt, among others.
Harbour's oil and gas production is forecast to rise from around 190,000 barrels per day to more than 500,000 per day following completion.