(Reuters) - Wireless carrier T-Mobile US expects to invest about $950 million for a 50% stake in a joint venture with Swedish investment firm EQT's fund that will buy fiber optic network provider Lumos, the companies said on Thursday. Washington-based T-Mobile will invest another $500 million between 2027 to 2028 to help Lumos reach 3.5 million homes by the end of the period. T-Mobile will acquire all existing fiber customers of Lumos as part of the deal with EQT's Infrastructure VI fund, which is expected to close in late 2024 or early 2025.