The FTSE 100 closed at 9,350.43 on Tuesday, capping a 6.7% third-quarter gain that marked London’s strongest summer index performance since 2016 even as official growth data stayed muted.

Who carried the index

Rolls-Royce Holdings pushed through a £100 billion market capitalisation during the month, ranking fifth among blue-chip constituents behind AstraZeneca, HSBC, Shell and Unilever. Investors have treated the engineer as a dual play on civil aviation recovery and power demand from data-centre expansion.

Banking stocks extended a year-long rally: HSBC shares rose 18.5% over the quarter, while Standard Chartered and Prudential posted double-digit gains. Defence names and gold miners also contributed as geopolitical tension kept haven demand elevated.

Energy as a counterweight

Oil majors slipped as crude prices retreated on talk of higher OPEC+ output and hopes for Middle East de-escalation. That drag prevented the index from holding intraday records set earlier in the week, but the quarterly picture still shows breadth beyond commodities.

GSK climbed 8.4% in September to its highest share price of the year, helping the healthcare cluster offset weakness in consumer staples.

Macro backdrop

The rally landed alongside unrevised second-quarter GDP growth of 0.3% and business-confidence surveys pointing to caution on hiring. For fund managers, the split underscores a market trading on sector cash flows and buybacks rather than a booming domestic economy.

With the Bank of England holding Bank Rate at 4% after its September meeting, dividend-heavy FTSE names continue to attract income funds rotating out of lower-yielding gilts.

Analysts said October will test whether Princes Group’s listing and any revived IPO pipeline can reverse London’s slide in global fundraising league tables without disturbing the index’s recent momentum.

Flows and foreign buyers

ETF providers reported net inflows into UK equity funds in September for the first time since April, helped by pension schemes rebalancing away from long-dated gilts. Sterling’s relative stability against the dollar kept hedging costs manageable for US allocators dipping back into London listings.

Retail investors using tax-efficient ISAs also contributed, according to platform data, with dividend reinvestment programmes automatically buying FTSE trackers on the final trading day of the quarter.

What could unsettle October

Traders flagged the US federal funding deadline and Middle East diplomacy as swing factors for energy names. Domestically, any surprise in October CPI could shift rate-cut bets and pressure rate-sensitive real-estate investment trusts that rallied alongside banks in Q3.

Wealth managers in the City said client questions focused on whether the record close justifies taking profits ahead of the autumn budget, a reminder that headline index levels do not always match household sentiment.