The objectives of this study were to investigate whether SNP effects can be accurately estimated when the algorithm for proven and young (APY) is used in single-step GBLUP (ssGBLUP), and how close indirect predictions, based on SNP effects, are to genomic EBV (GEBV) from regular ssGBLUP. Tests involved an American Angus data set with 8,221,346 animals phenotyped for birth weight (6.2M), weaning weight (6.8M), and post-weaning gain (3.4M). Genotypes for 80,993 animals were used. Among the genotyped animals, the youngest 15,040, born from 2013 to 2014, were used for validation. The reduced data set had genotypes and phenotypes up to 2012; the complete data set had genotypes up to 2014. Based on the reduced data set, GEBV were calculated using regular ssGBLUP with direct inversion of G (G⁻¹), and APY ssGBLUP (G⁻¹_APY) with 11,000 core animals. The SNP effects were calculated based on a) G⁻¹, b) G⁻¹_APY, c) inverse of the core portion of G (G⁻¹_core). Direct genomic values (DGV) for validation animals were obtained as the sum of SNP effects weighted by the genotype content, and the difference between pedigree and genomic base was added to obtain indirect predictions. The benchmark GEBV was obtained using regular ssGBLUP with complete data. Correlation between SNP effects obtained with G⁻¹ and G⁻¹_APY was >0.99; lower correlation (0.93) was observed when using G⁻¹_core. However, correlations between the benchmark GEBV and DGV from G⁻¹, G⁻¹_APY, and G⁻¹_core were all 0.99. The average difference between benchmark GEBV and DGV was 113.95, indicating a large bias. Indirect predictions that included DGV and the difference between pedigree and genomic base were unbiased. Accurate indirect predictions can be obtained when APY ssGBLUP is used. In addition, indirect predictions are comparable to GEBV after adjustments for a genomic base. Backsolving genomic predictions to SNP effects may require only a group of genotyped animals representing the dimensionality of the genomic information. The results obtained in this study are applicable to large genotyped populations.