Short answers, pulled from the story.
Northern Songs Ltd was founded on the 22nd of February 1963 by music publisher Dick James, artist manager Brian Epstein, and Beatles songwriters John Lennon and Paul McCartney. Dick James and his partner Charles Silver held a controlling 50 per cent stake, while Lennon and McCartney each received 20 per cent.
Northern Songs was floated on the London Stock Exchange in 1965 to reduce the income tax burden on its principals. The shares were offered at 66 pence each and the application lists were oversubscribed within sixty seconds, despite initial skepticism from financial institutions.
In March 1969, Dick James and his partner Charles Silver sold their shares in Northern Songs to Associated Television for £1,525,000, without notifying Lennon or McCartney or offering them the chance to buy the shares. Lennon and McCartney attempted to gain a controlling interest but lost the bidding war to Lew Grade.
Jackson purchased ATV Music, which held the Northern Songs catalogue, in a deal signed on the 10th of August 1985, for £24.4 million. His bid was accepted over a higher rival offer because he had completed due diligence beforehand and could close the transaction quickly. Paul McCartney had been given first right of refusal but did not bid, reportedly considering the price too high.
Northern Songs was dissolved in 1995, the same year Michael Jackson merged his ATV Music catalogue with Sony Music's publishing arm to form Sony/ATV Music Publishing. Jackson retained half ownership in the merged company, which was later renamed Sony Music Publishing in February 2021.
After the 1965 public listing, Lennon and McCartney each owned 15 per cent of Northern Songs, stakes worth £195,200 each. Dick James and Charles Silver together held 37.5 per cent as the company's chairmen, while Harrison and Starr together held 1.6 per cent.