Pharmaceuticals giant GlaxoSmithKline has raised $1.7bn through the sale of its entire shareholding in US firm Quest Diagnostics.After the tax man has taken his slice the company expects to receive cash proceeds of around $1.1bn.Around half the shares Glaxo offloaded were repurchased by Quest while the remainder were sold via a secondary public offering.Glaxo originally acquired its stake in Quest in 1999 as consideration for the sale of its clinical laboratories. It has steadily reduced its stake over the years but pulled the trigger on the sale of its remaining stake "to take advantage of favourable market conditions, thereby releasing funds from one of our non-core assets," said Glaxo's chief financial officer, Julian Heslop. "This divestment demonstrates our focus on generating attractive returns for our shareholders and our ability to monetise significant gains when appropriate," Heslop added.