Every iPhone investor I know does one of two things: the broker's app, or Yahoo Finance. Both are free. For most people, that is genuinely the whole decision. Fidelity, Schwab, and Vanguard all have iOS apps. Yahoo Finance has the watchlist-and-alerts setup half the investing internet already uses.
The real question isn't which app. It's what you're tracking. Price is easy and nearly useless. Every app shows price. What most apps don't show is whether your portfolio still looks like the plan: did your stock allocation drift from 80% to 88% after a good year? Are two of your funds quietly holding the same mega-caps? That's the tracking that matters, and it's where a mobile portfolio tracker app with alerts earns its keep. Price alerts are table stakes. Allocation-drift alerts are the upgrade. Check what an app actually pings you about before committing.
Still in the building phase? An ETF portfolio builder that starts from your target allocation serves you better than any tracker. For tracking itself, two criteria. First, does the app aggregate across brokerages, or only see one account? A tracker that sees half your money is a rumor, not a report. Second, alert quality: can you set thresholds that match your temperament, or does it spam you into muting everything by week two? Even the best ETF screener app in the world can't help if its alerts trained you to ignore them.
My goal with alerts is to check my portfolio less, not more. Set the guardrails, then go live your life.
When an alert tells you something drifted, compare before you act. ETFCompare is the ETF comparison tool I open first: 108 ETFs, fees and overlap side by side. Start at etfcompare.fyi.