You're a senior quantitative trader tasked with designing and implementing a robust statistical arbitrage portfolio for a high-frequency trading platform. Considering the current environment of increased market volatility, rising transaction costs, and extensive data availability (including historical stock prices, trading volumes, macroeconomic data, and news sentiment data), walk me through how you would approach building this portfolio. Please cover strategy selection, model development, risk management, backtesting and performance evaluation, and potential implementation challenges.

假设你是一名资深量化交易员，被要求为一个高频交易平台设计并实施一个稳健的统计套利投资组合。目前市场波动加剧，交易成本上升，数据可访问性很高，包括历史股票价格、交易量、宏观经济数据和新闻情绪数据。请你详细阐述如何构建这样一个投资组合。你需要从策略选择、模型构建、风险管理、回测与评估以及实际实施挑战等方面进行全面分析。