The Taylor Wimpey (LSE: TW) share price is responsible for the single biggest loss in my Self-Invested Personal Pension (SIPP) and Friday (31 July) inflicted still more misery. The shares were cheap, with a price-to-earnings ratio of around six or seven, and yielded north of 8%. Alas, all Taylor Wimpey has done is erode it. Taylor Wimpey expects to build fewer homes this year (between 10,600 and 10,800) excluding joint ventures. Taylor Wimpey shares look good value with a P/E ratio of 10.5.