Activist takeovers, company results, and a surprising infrastructure deal helped the ASX to a positive close on Monday, despite some volatile price moves.

The benchmark S&P/ASX 200 ended the day up 11.9 points, 0.2 per cent, at 7233.6 points. The index spent the morning in negative territory, but improved once futures indicated Wall Street would rise when trading resumes after a public holiday.

News was dominated by an attempted takeover of AGL Energy, with the prospect of a bidding war pushing shares up 10.6 per cent to a seven-month high of $7.92. Meanwhile, Telstra surprised the market by announcing plans to let a competitor onto its prized regional mobile network with long-time competitor TPG.

Chief investment officer at Australian Eagle Asset Management, Sean Sequeira, said his firm bought into Telstra about a year ago when the incumbent bundled up part of its mobile tower assets for sale.

“We liked the idea of them separating out the infrastructure assets,″⁣ he explained.

Telstra hit a four-year high of $4.26 in January, but declined in recent weeks. Shares closed 1.5 per cent higher at $3.97 on Monday. TPG shares jumped 3.1 per cent to a two-week high of $5.97.

Mr Sequeira said he would wait until the end of the reporting season to adjust his portfolio, but has been surprised by the size of reactions in some stock prices.

“We have had some winners and losers. Relative to other reporting seasons, we find it has been quite volatile.”

Five companies moved more than 10 per cent on Monday due to results or corporate activity.

The biggest move was a 25.9 per cent fall in Tyro Payments, which reported a larger than expected loss.

PointsBet Holdings fell 11.1 per cent After an international peer reported falling customer numbers.

Super Retail Group dropped 9.5 per cent after a 36 per cent fall in profit, and Zip Co dropped 7.8 per cent because early results foreshadowed a $108 million loss.

Meanwhile, a2 Milk jumped 11.1 per cent to a three-month high of $5.89 after its half-year results, and Woolie’s drinks spin-off Endeavour Group jumped 10.3 per cent to a three-month high of $7.18, thanks to Australians drinking at home more during the pandemic.

Outside of the big swings, the big banks closed higher, while BHP and Rio Tinto made small gains. Property owners also improved, with Centre Group, Dexus, and GPT Group higher.

However, the health sector dragged with CSL falling 0.8 per cent and Sonic Healthcare falling 3.6 per cent. Information technology was dragged down with heavyweight Block Inc setting 6.8 per cent to a new low of $133.80.