Number of data points on stock price chart

We're creating a graph where customers can see development of security price over time. We're going to use a line chart with which the user can interact by tap/hold gesture to see different data points and their values on the graph.

Question is - how many data points does it make sense to have on the graph to still have it usable? If we're talking a data point per week for 5 years that's 5*52=260 points which seems like a lot for mobile device to interact with (especially on smaller devices like iPhone 5/SE, etc).

However reducing data points makes the graph less granular (which depending on user/use cases might be okay). Any suggestions on how to approach this?