GSK (LSE: GSK) shares have been a massive disappointment since I added them to my Self-Invested Personal Pension in March and June last year. So far, I’m down around 15% and can’t see much sign of a recovery.

The shares are down 6.5% over the last 12 months and more than 12% over five years. With dividends under pressure too, it’s been disappointing all round.

The FTSE 100 pharmaceutical giant has been a dismal investment for a decade. Ten years ago, the shares traded at 1,351p. Today they’re at 1,426p, an increase of just 5.5%.

Growth issues

That would have turned a £10,000 investment into just £10,550. Yes, investors would have collected plenty dividends, but paid at much lower levels than many would have expected.

The dividend was frozen at 80p in 2014, then held for seven years. It was then slashed 28% to 57.75p in 2022. The polite word for that is ‘rebasing’. I have others!

Since then, it’s edged up. GSK paid 58p in 2023 and 61p last year, the same as it paid in 2009. It expects to pay 64p in 2025

CEO Emma Walmsley has been battling to rebuild the pipeline since her appointment in 2017. On paper, things are improving. In Q1 2025, published on 30 April, total sales rose 4% to £7.5bn. Specialty Medicines jumped 17% to £2.9bn, with growth in oncology, respiratory and HIV.

Profits are up

Operating profit soared 50%, while core EPS rose 5%. GSK generated £1bn in cash and bought back £273m of shares as the first part of a £2bn programme.

Yet sentiment remains weak. The P/E is just 8.85, reflecting the huge uncertainty now hanging over the sector. In February, it emerged that hedge fund billionaire Ken Griffin has reportedly been building a £305m short position against GSK.

The main threat lies in the US, which made up more than half of its revenues last year, as Donald Trump threatens steep tariffs on imported medicines and health secretary Robert F Kennedy Jr raises questions about vaccines. Food and Drug Administration staff cuts could slow drug approvals.

GSK also faces a looming patent cliff. Its HIV blockbuster dolutegravir loses exclusivity between 2028 and 2030. It made £5.6bn last year, nearly 20% of group sales.

FTSE 100 underperformer

There are glimmers of hope. GSK just paid £950m for US biotech IDRx and says 14 drugs in its pipeline could each bring in more than £2bn a year.

Of the 21 analysts covering the stock, 13 say Hold. I think that sums up the situation nicely. Their median forecast suggest the shares will hit 1,636p in a year, a gain of around 15%. Add the forecast 4.48% yield and the total prospective return rises to 19.5%.

I’d be thrilled if that happens. And very surprised. I think I’ve made a bad call here. I certainly wouldn’t consider buying the stock today. Its short-to-medium-term future is now in the hands of Donald Trump, rather than its own. Not an ideal place to be.