Stockwatch

The week's winnersAtrium up 3.2%Aviva up 3.1%

The week's losersHardy down 5.6%SVB down 2.8%The US has a new giant of commercial insurance.The St Paul Companies and Travelers Property Casualty have agreed to merge, to the general delight of analysts.They become the second largest commercial insurer in the US with 7.6% market share, behind AIG, controlling assets of $107bn, with a remarkably neat geographic fit between its two halves.Rowena Potter, credit analyst at Standard & Poor's ratings agency, said the impact on UK insurers would most likely be neutral but added: "Everybody will be watching to see if they can find some good synergies and bring costs down."Investors appear to be seeing signs of value in GoshawK since the departure of chief executive Chris Fagan and the company forced out of Lloyd's.Aberforth went as far as buying 793,000 shares, or 0.4%, last week taking its total holding to nearly 5.5 million shares, or 3.1% of the group.Ratings agency AM Best downgraded Chicago-based CNA to A from A+ after it announced it had strengthened its reserves to the tune of $1.8bn.It put $978m into core reserves, $517m into asbestos and environmental reserves and $332m into bad debt reserves.Is it time for SVB to end the bear run on its shares? The stock has spent the last three months in gradual decline from a 52-week high of 68p in early September to its current level of a shade over 50p.Rumours abound that ex-PRI man Peter Matson is going to rejoin some of his old colleagues by moving to SVB. With a £50m bond issue underway, the insurer has an agenda that would suit Matson down to the ground and bring relief to brokers still struggling to place small and mid-sized UK regional PI risks.