The ASX underperformed regional markets again this week, with losses compounded by breaking news this afternoon that President Trump has tested positive to COVID-19. By the close of trade on Friday, the ASX 200 was sitting on 5,791.50 points, 2.9% lower than the start of the week. It marked the worst weekly performance for the local market since late April, despite the easing of border restrictions signalled for several parts of the country.

Which shares excelled?

Asset management company Janus Henderson Group (ASX: JHG) climbed 16.7% this week on heavy offshore buying interest. It came as activist investment firm Trian Fund Management took a 9.9% stake in the company. The activist investor also bought a similar-sized stake in Invesco, an American investment management company. The move sparked speculation that Janus Henderson Group could be subject to M&A activity given Trian history as a fund with a goal of driving consolidation in the asset management industry.There was positive news for ASX travel stocks, with the government confirming that the Australia-NZ border bubble would commence starting October 16th. While the arrangement is initially limited to cater to inbound tourists from New Zealand in New South Wales and Northern Territory, it is expected that the scheme may widen in due course.Furthermore, there were also several adjustments made to state border policies, including a target date of November 1st to reopen the Queensland and NSW border. Each of Air New Zealand (ASX: AIZ), Webjet (ASX: WEB), Corporate Travel Management (ASX: CTD), Flight Centre (ASX: FLT) and Qantas (ASX: QAN) performed strongly.Digital payment stocks were in high demand this week, despite a haircut to gains on news of President Trump COVID diagnosis. Shares such as Zip Co (ASX: Z1P), Sezzle (ASX: SZL), EML Payments (ASX: EML) and Afterpay (ASX: APT) all managed to rise throughout the week, even though there were no sector-wide catalysts driving sentiment. Zip annual report, however, was received positively by the market.Elsewhere, Premier Investments (ASX: PMV) had a bumper result following a suite of broker upgrades at the start of the week in the wake of its FY20 earnings. The retailer gained 11.9% across the week, while its sector peer Temple & Webster (ASX: TPW) continued its fine form of late, advancing 6.6%.Some of the other notable names to chalk out modest increases this week were Boral (ASX: BLD), Credit Corp Group (ASX: CCP), Reliance Worldwide (ASX: RWC), Nearmap (ASX: NEA), Xero (ASX: XRO) and Lynas (ASX: LYC).

Which shares dragged on the market?

After its highly-awaited announcement fell short of expectations, Mesoblast (ASX: MSB) shares tanked 35.4% this week. The stem cell biotechnology firm was caught on the back foot by news that the US Food and Drug Administration (FDA) is asking for further evidence regarding the effectiveness of its remestemcel-L treatment before it would be in the position to grant approval.

Although the FDA advisory committee supported the efficacy of Mesoblast treatment in an August vote, the setback disappointed shareholders and will now see the company rework its timeline in consultation with the regulator.

Earlier in the week, A2 Milk (ASX: A2M) shares dived on news relating to subdued sales stemming from the daigou channel. The impact of stage four lockdown restrictions in Victoria have weighed on the level of replenishment in orders that were expected in relation to resellers.Pantry destocking also weighed on sales growth for A2 Milk, leading the company to cut its forecast for first-half sales in FY21. Shares in A2M sunk 18.5%, with the news also weighing on vitamins and infant formula business Blackmores (ASX: BKL), which has exposure to the daigou channel. As a result, Blackmores shares slipped 11.1% this week.With the price of oil dropping sharply in recent days, energy stocks were all subject to heavy selling pressure, many approaching multi-month lows. Among those hit were companies like Beach Energy (ASX: BPT), Santos (ASX: STO), Woodside Petroleum (ASX: WPL) and Oil Search (ASX: OSH).In news that rocked shareholders, management of Bank of Queensland (ASX: BOQ) announced that loan impairment expenses for FY20 would total $175 million before tax. This was equivalent to a 37 basis point hit to gross loans, also leading to an impact on the company CET1 ratio. The stock shed 9.5% this week as investors erred on the side of caution.Rounding things out, there were also prominent losses for the likes of OceanaGold Corporation (ASX: OGC), BHP (ASX: BHP), AGL (ASX: AGL), Transurban (ASX: TCL), Incitec Pivot (ASX: IPL) and Metcash (ASX: MTS).

We'll be back next week with another Weekly ASX Trading Wrap Up - until then, have a great weekend!