app.py

import streamlit as st
import yfinance as yf
import pandas as pd
import matplotlib.pyplot as plt

st.title('Stock vs S&P 500 and Dow Jones Comparison')

# User input
user_stock = st.text_input('Enter a stock symbol (e.g., AAPL, TSLA, MSFT)', 'MAR')

if user_stock:
    tickers = [user_stock.upper(), '^GSPC', '^DJI']
    
    try:
        # Download past 1 year of daily data
        data = yf.download(tickers, period='1y', interval='1d')

        # Check if user stock symbol returned data
        if data.empty or user_stock.upper() not in data.columns.get_level_values(1):
            st.error('Not a valid stock symbol')
        else:
            # If MultiIndex, focus on 'Close' prices
            if isinstance(data.columns, pd.MultiIndex):
                close_prices = data['Close']
            else:
                close_prices = data

            # Normalize (start at 100)
            normalized = close_prices / close_prices.iloc[0] * 100

            # Plot
            fig, ax = plt.subplots(figsize=(12, 6))
            for column in normalized.columns:
                ax.plot(normalized.index, normalized[column], label=column)

            ax.set_title(f'{user_stock.upper()} vs S&P 500 vs Dow Jones (Past 1 Year)')
            ax.set_xlabel('Date')
            ax.set_ylabel('Normalized Price (Start = 100)')
            ax.legend()
            ax.grid(True)
            st.pyplot(fig)
    except Exception as e:
        st.error('Not a valid stock symbol')